sys/kern/uipc_shm.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause
   3  *
   4  * Copyright (c) 2006, 2011, 2016-2017 Robert N. M. Watson
   5  * Copyright 2020 The FreeBSD Foundation
   6  * All rights reserved.
   7  *
   8  * Portions of this software were developed by BAE Systems, the University of
   9  * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL
  10  * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent
  11  * Computing (TC) research program.
  12  *
  13  * Portions of this software were developed by Konstantin Belousov
  14  * under sponsorship from the FreeBSD Foundation.
  15  *
  16  * Redistribution and use in source and binary forms, with or without
  17  * modification, are permitted provided that the following conditions
  18  * are met:
  19  * 1. Redistributions of source code must retain the above copyright
  20  *    notice, this list of conditions and the following disclaimer.
  21  * 2. Redistributions in binary form must reproduce the above copyright
  22  *    notice, this list of conditions and the following disclaimer in the
  23  *    documentation and/or other materials provided with the distribution.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  */
  37
  38 /*
  39  * Support for shared swap-backed anonymous memory objects via
  40  * shm_open(2), shm_rename(2), and shm_unlink(2).
  41  * While most of the implementation is here, vm_mmap.c contains
  42  * mapping logic changes.
  43  *
  44  * posixshmcontrol(1) allows users to inspect the state of the memory
  45  * objects.  Per-uid swap resource limit controls total amount of
  46  * memory that user can consume for anonymous objects, including
  47  * shared.
  48  */
  49
  50 #include <sys/cdefs.h>
  51 #include "opt_capsicum.h"
  52 #include "opt_ktrace.h"
  53
  54 #include <sys/param.h>
  55 #include <sys/capsicum.h>
  56 #include <sys/conf.h>
  57 #include <sys/fcntl.h>
  58 #include <sys/file.h>
  59 #include <sys/filedesc.h>
  60 #include <sys/filio.h>
  61 #include <sys/fnv_hash.h>
  62 #include <sys/kernel.h>
  63 #include <sys/limits.h>
  64 #include <sys/uio.h>
  65 #include <sys/signal.h>
  66 #include <sys/jail.h>
  67 #include <sys/ktrace.h>
  68 #include <sys/lock.h>
  69 #include <sys/malloc.h>
  70 #include <sys/mman.h>
  71 #include <sys/mutex.h>
  72 #include <sys/priv.h>
  73 #include <sys/proc.h>
  74 #include <sys/refcount.h>
  75 #include <sys/resourcevar.h>
  76 #include <sys/rwlock.h>
  77 #include <sys/sbuf.h>
  78 #include <sys/stat.h>
  79 #include <sys/syscallsubr.h>
  80 #include <sys/sysctl.h>
  81 #include <sys/sysproto.h>
  82 #include <sys/systm.h>
  83 #include <sys/sx.h>
  84 #include <sys/time.h>
  85 #include <sys/vmmeter.h>
  86 #include <sys/vnode.h>
  87 #include <sys/unistd.h>
  88 #include <sys/user.h>
  89
  90 #include <security/audit/audit.h>
  91 #include <security/mac/mac_framework.h>
  92
  93 #include <vm/vm.h>
  94 #include <vm/vm_param.h>
  95 #include <vm/pmap.h>
  96 #include <vm/vm_extern.h>
  97 #include <vm/vm_map.h>
  98 #include <vm/vm_kern.h>
  99 #include <vm/vm_object.h>
 100 #include <vm/vm_page.h>
 101 #include <vm/vm_pageout.h>
 102 #include <vm/vm_pager.h>
 103 #include <vm/swap_pager.h>
 104
 105 struct shm_mapping {
 106         char            *sm_path;
 107         Fnv32_t         sm_fnv;
 108         struct shmfd    *sm_shmfd;
 109         LIST_ENTRY(shm_mapping) sm_link;
 110 };
 111
 112 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor");
 113 static LIST_HEAD(, shm_mapping) *shm_dictionary;
 114 static struct sx shm_dict_lock;
 115 static struct mtx shm_timestamp_lock;
 116 static u_long shm_hash;
 117 static struct unrhdr64 shm_ino_unr;
 118 static dev_t shm_dev_ino;
 119
 120 #define SHM_HASH(fnv)   (&shm_dictionary[(fnv) & shm_hash])
 121
 122 static void     shm_init(void *arg);
 123 static void     shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd);
 124 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv);
 125 static int      shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
 126 static void     shm_doremove(struct shm_mapping *map);
 127 static int      shm_dotruncate_cookie(struct shmfd *shmfd, off_t length,
 128     void *rl_cookie);
 129 static int      shm_dotruncate_locked(struct shmfd *shmfd, off_t length,
 130     void *rl_cookie);
 131 static int      shm_copyin_path(struct thread *td, const char *userpath_in,
 132     char **path_out);
 133 static int      shm_deallocate(struct shmfd *shmfd, off_t *offset,
 134     off_t *length, int flags);
 135
 136 static fo_rdwr_t        shm_read;
 137 static fo_rdwr_t        shm_write;
 138 static fo_truncate_t    shm_truncate;
 139 static fo_ioctl_t       shm_ioctl;
 140 static fo_stat_t        shm_stat;
 141 static fo_close_t       shm_close;
 142 static fo_chmod_t       shm_chmod;
 143 static fo_chown_t       shm_chown;
 144 static fo_seek_t        shm_seek;
 145 static fo_fill_kinfo_t  shm_fill_kinfo;
 146 static fo_mmap_t        shm_mmap;
 147 static fo_get_seals_t   shm_get_seals;
 148 static fo_add_seals_t   shm_add_seals;
 149 static fo_fallocate_t   shm_fallocate;
 150 static fo_fspacectl_t   shm_fspacectl;
 151
 152 /* File descriptor operations. */
 153 struct fileops shm_ops = {
 154         .fo_read = shm_read,
 155         .fo_write = shm_write,
 156         .fo_truncate = shm_truncate,
 157         .fo_ioctl = shm_ioctl,
 158         .fo_poll = invfo_poll,
 159         .fo_kqfilter = invfo_kqfilter,
 160         .fo_stat = shm_stat,
 161         .fo_close = shm_close,
 162         .fo_chmod = shm_chmod,
 163         .fo_chown = shm_chown,
 164         .fo_sendfile = vn_sendfile,
 165         .fo_seek = shm_seek,
 166         .fo_fill_kinfo = shm_fill_kinfo,
 167         .fo_mmap = shm_mmap,
 168         .fo_get_seals = shm_get_seals,
 169         .fo_add_seals = shm_add_seals,
 170         .fo_fallocate = shm_fallocate,
 171         .fo_fspacectl = shm_fspacectl,
 172         .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE,
 173 };
 174
 175 FEATURE(posix_shm, "POSIX shared memory");
 176
 177 static SYSCTL_NODE(_vm, OID_AUTO, largepages, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
 178     "");
 179
 180 static int largepage_reclaim_tries = 1;
 181 SYSCTL_INT(_vm_largepages, OID_AUTO, reclaim_tries,
 182     CTLFLAG_RWTUN, &largepage_reclaim_tries, 0,
 183     "Number of contig reclaims before giving up for default alloc policy");
 184
 185 #define shm_rangelock_unlock(shmfd, cookie)                             \
 186         rangelock_unlock(&(shmfd)->shm_rl, (cookie), &(shmfd)->shm_mtx)
 187 #define shm_rangelock_rlock(shmfd, start, end)                          \
 188         rangelock_rlock(&(shmfd)->shm_rl, (start), (end), &(shmfd)->shm_mtx)
 189 #define shm_rangelock_tryrlock(shmfd, start, end)                       \
 190         rangelock_tryrlock(&(shmfd)->shm_rl, (start), (end), &(shmfd)->shm_mtx)
 191 #define shm_rangelock_wlock(shmfd, start, end)                          \
 192         rangelock_wlock(&(shmfd)->shm_rl, (start), (end), &(shmfd)->shm_mtx)
 193
 194 static int
 195 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio)
 196 {
 197         vm_page_t m;
 198         vm_pindex_t idx;
 199         size_t tlen;
 200         int error, offset, rv;
 201
 202         idx = OFF_TO_IDX(uio->uio_offset);
 203         offset = uio->uio_offset & PAGE_MASK;
 204         tlen = MIN(PAGE_SIZE - offset, len);
 205
 206         rv = vm_page_grab_valid_unlocked(&m, obj, idx,
 207             VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY | VM_ALLOC_NOCREAT);
 208         if (rv == VM_PAGER_OK)
 209                 goto found;
 210
 211         /*
 212          * Read I/O without either a corresponding resident page or swap
 213          * page: use zero_region.  This is intended to avoid instantiating
 214          * pages on read from a sparse region.
 215          */
 216         VM_OBJECT_WLOCK(obj);
 217         m = vm_page_lookup(obj, idx);
 218         if (uio->uio_rw == UIO_READ && m == NULL &&
 219             !vm_pager_has_page(obj, idx, NULL, NULL)) {
 220                 VM_OBJECT_WUNLOCK(obj);
 221                 return (uiomove(__DECONST(void *, zero_region), tlen, uio));
 222         }
 223
 224         /*
 225          * Although the tmpfs vnode lock is held here, it is
 226          * nonetheless safe to sleep waiting for a free page.  The
 227          * pageout daemon does not need to acquire the tmpfs vnode
 228          * lock to page out tobj's pages because tobj is a OBJT_SWAP
 229          * type object.
 230          */
 231         rv = vm_page_grab_valid(&m, obj, idx,
 232             VM_ALLOC_NORMAL | VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY);
 233         if (rv != VM_PAGER_OK) {
 234                 VM_OBJECT_WUNLOCK(obj);
 235                 if (bootverbose) {
 236                         printf("uiomove_object: vm_obj %p idx %jd "
 237                             "pager error %d\n", obj, idx, rv);
 238                 }
 239                 return (rv == VM_PAGER_AGAIN ? ENOSPC : EIO);
 240         }
 241         VM_OBJECT_WUNLOCK(obj);
 242
 243 found:
 244         error = uiomove_fromphys(&m, offset, tlen, uio);
 245         if (uio->uio_rw == UIO_WRITE && error == 0)
 246                 vm_page_set_dirty(m);
 247         vm_page_activate(m);
 248         vm_page_sunbusy(m);
 249
 250         return (error);
 251 }
 252
 253 int
 254 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio)
 255 {
 256         ssize_t resid;
 257         size_t len;
 258         int error;
 259
 260         error = 0;
 261         while ((resid = uio->uio_resid) > 0) {
 262                 if (obj_size <= uio->uio_offset)
 263                         break;
 264                 len = MIN(obj_size - uio->uio_offset, resid);
 265                 if (len == 0)
 266                         break;
 267                 error = uiomove_object_page(obj, len, uio);
 268                 if (error != 0 || resid == uio->uio_resid)
 269                         break;
 270         }
 271         return (error);
 272 }
 273
 274 static u_long count_largepages[MAXPAGESIZES];
 275
 276 static int
 277 shm_largepage_phys_populate(vm_object_t object, vm_pindex_t pidx,
 278     int fault_type, vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last)
 279 {
 280         vm_page_t m __diagused;
 281         int psind;
 282
 283         psind = object->un_pager.phys.data_val;
 284         if (psind == 0 || pidx >= object->size)
 285                 return (VM_PAGER_FAIL);
 286         *first = rounddown2(pidx, pagesizes[psind] / PAGE_SIZE);
 287
 288         /*
 289          * We only busy the first page in the superpage run.  It is
 290          * useless to busy whole run since we only remove full
 291          * superpage, and it takes too long to busy e.g. 512 * 512 ==
 292          * 262144 pages constituing 1G amd64 superage.
 293          */
 294         m = vm_page_grab(object, *first, VM_ALLOC_NORMAL | VM_ALLOC_NOCREAT);
 295         MPASS(m != NULL);
 296
 297         *last = *first + atop(pagesizes[psind]) - 1;
 298         return (VM_PAGER_OK);
 299 }
 300
 301 static boolean_t
 302 shm_largepage_phys_haspage(vm_object_t object, vm_pindex_t pindex,
 303     int *before, int *after)
 304 {
 305         int psind;
 306
 307         psind = object->un_pager.phys.data_val;
 308         if (psind == 0 || pindex >= object->size)
 309                 return (FALSE);
 310         if (before != NULL) {
 311                 *before = pindex - rounddown2(pindex, pagesizes[psind] /
 312                     PAGE_SIZE);
 313         }
 314         if (after != NULL) {
 315                 *after = roundup2(pindex, pagesizes[psind] / PAGE_SIZE) -
 316                     pindex;
 317         }
 318         return (TRUE);
 319 }
 320
 321 static void
 322 shm_largepage_phys_ctor(vm_object_t object, vm_prot_t prot,
 323     vm_ooffset_t foff, struct ucred *cred)
 324 {
 325 }
 326
 327 static void
 328 shm_largepage_phys_dtor(vm_object_t object)
 329 {
 330         int psind;
 331
 332         psind = object->un_pager.phys.data_val;
 333         if (psind != 0) {
 334                 atomic_subtract_long(&count_largepages[psind],
 335                     object->size / (pagesizes[psind] / PAGE_SIZE));
 336                 vm_wire_sub(object->size);
 337         } else {
 338                 KASSERT(object->size == 0,
 339                     ("largepage phys obj %p not initialized bit size %#jx > 0",
 340                     object, (uintmax_t)object->size));
 341         }
 342 }
 343
 344 static const struct phys_pager_ops shm_largepage_phys_ops = {
 345         .phys_pg_populate =     shm_largepage_phys_populate,
 346         .phys_pg_haspage =      shm_largepage_phys_haspage,
 347         .phys_pg_ctor =         shm_largepage_phys_ctor,
 348         .phys_pg_dtor =         shm_largepage_phys_dtor,
 349 };
 350
 351 bool
 352 shm_largepage(struct shmfd *shmfd)
 353 {
 354         return (shmfd->shm_object->type == OBJT_PHYS);
 355 }
 356
 357 static void
 358 shm_pager_freespace(vm_object_t obj, vm_pindex_t start, vm_size_t size)
 359 {
 360         struct shmfd *shm;
 361         vm_size_t c;
 362
 363         swap_pager_freespace(obj, start, size, &c);
 364         if (c == 0)
 365                 return;
 366
 367         shm = obj->un_pager.swp.swp_priv;
 368         if (shm == NULL)
 369                 return;
 370         KASSERT(shm->shm_pages >= c,
 371             ("shm %p pages %jd free %jd", shm,
 372             (uintmax_t)shm->shm_pages, (uintmax_t)c));
 373         shm->shm_pages -= c;
 374 }
 375
 376 static void
 377 shm_page_inserted(vm_object_t obj, vm_page_t m)
 378 {
 379         struct shmfd *shm;
 380
 381         shm = obj->un_pager.swp.swp_priv;
 382         if (shm == NULL)
 383                 return;
 384         if (!vm_pager_has_page(obj, m->pindex, NULL, NULL))
 385                 shm->shm_pages += 1;
 386 }
 387
 388 static void
 389 shm_page_removed(vm_object_t obj, vm_page_t m)
 390 {
 391         struct shmfd *shm;
 392
 393         shm = obj->un_pager.swp.swp_priv;
 394         if (shm == NULL)
 395                 return;
 396         if (!vm_pager_has_page(obj, m->pindex, NULL, NULL)) {
 397                 KASSERT(shm->shm_pages >= 1,
 398                     ("shm %p pages %jd free 1", shm,
 399                     (uintmax_t)shm->shm_pages));
 400                 shm->shm_pages -= 1;
 401         }
 402 }
 403
 404 static struct pagerops shm_swap_pager_ops = {
 405         .pgo_kvme_type = KVME_TYPE_SWAP,
 406         .pgo_freespace = shm_pager_freespace,
 407         .pgo_page_inserted = shm_page_inserted,
 408         .pgo_page_removed = shm_page_removed,
 409 };
 410 static int shmfd_pager_type = -1;
 411
 412 static int
 413 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td)
 414 {
 415         struct shmfd *shmfd;
 416         off_t foffset;
 417         int error;
 418
 419         shmfd = fp->f_data;
 420         foffset = foffset_lock(fp, 0);
 421         error = 0;
 422         switch (whence) {
 423         case L_INCR:
 424                 if (foffset < 0 ||
 425                     (offset > 0 && foffset > OFF_MAX - offset)) {
 426                         error = EOVERFLOW;
 427                         break;
 428                 }
 429                 offset += foffset;
 430                 break;
 431         case L_XTND:
 432                 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) {
 433                         error = EOVERFLOW;
 434                         break;
 435                 }
 436                 offset += shmfd->shm_size;
 437                 break;
 438         case L_SET:
 439                 break;
 440         default:
 441                 error = EINVAL;
 442         }
 443         if (error == 0) {
 444                 if (offset < 0 || offset > shmfd->shm_size)
 445                         error = EINVAL;
 446                 else
 447                         td->td_uretoff.tdu_off = offset;
 448         }
 449         foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
 450         return (error);
 451 }
 452
 453 static int
 454 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
 455     int flags, struct thread *td)
 456 {
 457         struct shmfd *shmfd;
 458         void *rl_cookie;
 459         int error;
 460
 461         shmfd = fp->f_data;
 462 #ifdef MAC
 463         error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd);
 464         if (error)
 465                 return (error);
 466 #endif
 467         foffset_lock_uio(fp, uio, flags);
 468         rl_cookie = shm_rangelock_rlock(shmfd, uio->uio_offset,
 469             uio->uio_offset + uio->uio_resid);
 470         error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
 471         shm_rangelock_unlock(shmfd, rl_cookie);
 472         foffset_unlock_uio(fp, uio, flags);
 473         return (error);
 474 }
 475
 476 static int
 477 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
 478     int flags, struct thread *td)
 479 {
 480         struct shmfd *shmfd;
 481         void *rl_cookie;
 482         int error;
 483         off_t size;
 484
 485         shmfd = fp->f_data;
 486 #ifdef MAC
 487         error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd);
 488         if (error)
 489                 return (error);
 490 #endif
 491         if (shm_largepage(shmfd) && shmfd->shm_lp_psind == 0)
 492                 return (EINVAL);
 493         foffset_lock_uio(fp, uio, flags);
 494         if (uio->uio_resid > OFF_MAX - uio->uio_offset) {
 495                 /*
 496                  * Overflow is only an error if we're supposed to expand on
 497                  * write.  Otherwise, we'll just truncate the write to the
 498                  * size of the file, which can only grow up to OFF_MAX.
 499                  */
 500                 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0) {
 501                         foffset_unlock_uio(fp, uio, flags);
 502                         return (EFBIG);
 503                 }
 504
 505                 size = shmfd->shm_size;
 506         } else {
 507                 size = uio->uio_offset + uio->uio_resid;
 508         }
 509         if ((flags & FOF_OFFSET) == 0)
 510                 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
 511         else
 512                 rl_cookie = shm_rangelock_wlock(shmfd, uio->uio_offset, size);
 513         if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) {
 514                 error = EPERM;
 515         } else {
 516                 error = 0;
 517                 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0 &&
 518                     size > shmfd->shm_size) {
 519                         error = shm_dotruncate_cookie(shmfd, size, rl_cookie);
 520                 }
 521                 if (error == 0)
 522                         error = uiomove_object(shmfd->shm_object,
 523                             shmfd->shm_size, uio);
 524         }
 525         shm_rangelock_unlock(shmfd, rl_cookie);
 526         foffset_unlock_uio(fp, uio, flags);
 527         return (error);
 528 }
 529
 530 static int
 531 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
 532     struct thread *td)
 533 {
 534         struct shmfd *shmfd;
 535 #ifdef MAC
 536         int error;
 537 #endif
 538
 539         shmfd = fp->f_data;
 540 #ifdef MAC
 541         error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
 542         if (error)
 543                 return (error);
 544 #endif
 545         return (shm_dotruncate(shmfd, length));
 546 }
 547
 548 int
 549 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred,
 550     struct thread *td)
 551 {
 552         struct shmfd *shmfd;
 553         struct shm_largepage_conf *conf;
 554         void *rl_cookie;
 555
 556         shmfd = fp->f_data;
 557         switch (com) {
 558         case FIONBIO:
 559         case FIOASYNC:
 560                 /*
 561                  * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work,
 562                  * just like it would on an unlinked regular file
 563                  */
 564                 return (0);
 565         case FIOSSHMLPGCNF:
 566                 if (!shm_largepage(shmfd))
 567                         return (ENOTTY);
 568                 conf = data;
 569                 if (shmfd->shm_lp_psind != 0 &&
 570                     conf->psind != shmfd->shm_lp_psind)
 571                         return (EINVAL);
 572                 if (conf->psind <= 0 || conf->psind >= MAXPAGESIZES ||
 573                     pagesizes[conf->psind] == 0)
 574                         return (EINVAL);
 575                 if (conf->alloc_policy != SHM_LARGEPAGE_ALLOC_DEFAULT &&
 576                     conf->alloc_policy != SHM_LARGEPAGE_ALLOC_NOWAIT &&
 577                     conf->alloc_policy != SHM_LARGEPAGE_ALLOC_HARD)
 578                         return (EINVAL);
 579
 580                 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
 581                 shmfd->shm_lp_psind = conf->psind;
 582                 shmfd->shm_lp_alloc_policy = conf->alloc_policy;
 583                 shmfd->shm_object->un_pager.phys.data_val = conf->psind;
 584                 shm_rangelock_unlock(shmfd, rl_cookie);
 585                 return (0);
 586         case FIOGSHMLPGCNF:
 587                 if (!shm_largepage(shmfd))
 588                         return (ENOTTY);
 589                 conf = data;
 590                 rl_cookie = shm_rangelock_rlock(shmfd, 0, OFF_MAX);
 591                 conf->psind = shmfd->shm_lp_psind;
 592                 conf->alloc_policy = shmfd->shm_lp_alloc_policy;
 593                 shm_rangelock_unlock(shmfd, rl_cookie);
 594                 return (0);
 595         default:
 596                 return (ENOTTY);
 597         }
 598 }
 599
 600 static int
 601 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred)
 602 {
 603         struct shmfd *shmfd;
 604 #ifdef MAC
 605         int error;
 606 #endif
 607
 608         shmfd = fp->f_data;
 609
 610 #ifdef MAC
 611         error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
 612         if (error)
 613                 return (error);
 614 #endif
 615
 616         /*
 617          * Attempt to return sanish values for fstat() on a memory file
 618          * descriptor.
 619          */
 620         bzero(sb, sizeof(*sb));
 621         sb->st_blksize = PAGE_SIZE;
 622         sb->st_size = shmfd->shm_size;
 623         mtx_lock(&shm_timestamp_lock);
 624         sb->st_atim = shmfd->shm_atime;
 625         sb->st_ctim = shmfd->shm_ctime;
 626         sb->st_mtim = shmfd->shm_mtime;
 627         sb->st_birthtim = shmfd->shm_birthtime;
 628         sb->st_mode = S_IFREG | shmfd->shm_mode;                /* XXX */
 629         sb->st_uid = shmfd->shm_uid;
 630         sb->st_gid = shmfd->shm_gid;
 631         mtx_unlock(&shm_timestamp_lock);
 632         sb->st_dev = shm_dev_ino;
 633         sb->st_ino = shmfd->shm_ino;
 634         sb->st_nlink = shmfd->shm_object->ref_count;
 635         if (shm_largepage(shmfd)) {
 636                 sb->st_blocks = shmfd->shm_object->size /
 637                     (pagesizes[shmfd->shm_lp_psind] >> PAGE_SHIFT);
 638         } else {
 639                 sb->st_blocks = shmfd->shm_pages;
 640         }
 641
 642         return (0);
 643 }
 644
 645 static int
 646 shm_close(struct file *fp, struct thread *td)
 647 {
 648         struct shmfd *shmfd;
 649
 650         shmfd = fp->f_data;
 651         fp->f_data = NULL;
 652         shm_drop(shmfd);
 653
 654         return (0);
 655 }
 656
 657 static int
 658 shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) {
 659         int error;
 660         char *path;
 661         const char *pr_path;
 662         size_t pr_pathlen;
 663
 664         path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
 665         pr_path = td->td_ucred->cr_prison->pr_path;
 666
 667         /* Construct a full pathname for jailed callers. */
 668         pr_pathlen = strcmp(pr_path, "/") ==
 669             0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN);
 670         error = copyinstr(userpath_in, path + pr_pathlen,
 671             MAXPATHLEN - pr_pathlen, NULL);
 672         if (error != 0)
 673                 goto out;
 674
 675 #ifdef KTRACE
 676         if (KTRPOINT(curthread, KTR_NAMEI))
 677                 ktrnamei(path);
 678 #endif
 679
 680         /* Require paths to start with a '/' character. */
 681         if (path[pr_pathlen] != '/') {
 682                 error = EINVAL;
 683                 goto out;
 684         }
 685
 686         *path_out = path;
 687
 688 out:
 689         if (error != 0)
 690                 free(path, M_SHMFD);
 691
 692         return (error);
 693 }
 694
 695 static int
 696 shm_partial_page_invalidate(vm_object_t object, vm_pindex_t idx, int base,
 697     int end)
 698 {
 699         vm_page_t m;
 700         int rv;
 701
 702         VM_OBJECT_ASSERT_WLOCKED(object);
 703         KASSERT(base >= 0, ("%s: base %d", __func__, base));
 704         KASSERT(end - base <= PAGE_SIZE, ("%s: base %d end %d", __func__, base,
 705             end));
 706
 707 retry:
 708         m = vm_page_grab(object, idx, VM_ALLOC_NOCREAT);
 709         if (m != NULL) {
 710                 MPASS(vm_page_all_valid(m));
 711         } else if (vm_pager_has_page(object, idx, NULL, NULL)) {
 712                 m = vm_page_alloc(object, idx,
 713                     VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL);
 714                 if (m == NULL)
 715                         goto retry;
 716                 vm_object_pip_add(object, 1);
 717                 VM_OBJECT_WUNLOCK(object);
 718                 rv = vm_pager_get_pages(object, &m, 1, NULL, NULL);
 719                 VM_OBJECT_WLOCK(object);
 720                 vm_object_pip_wakeup(object);
 721                 if (rv == VM_PAGER_OK) {
 722                         /*
 723                          * Since the page was not resident, and therefore not
 724                          * recently accessed, immediately enqueue it for
 725                          * asynchronous laundering.  The current operation is
 726                          * not regarded as an access.
 727                          */
 728                         vm_page_launder(m);
 729                 } else {
 730                         vm_page_free(m);
 731                         VM_OBJECT_WUNLOCK(object);
 732                         return (EIO);
 733                 }
 734         }
 735         if (m != NULL) {
 736                 pmap_zero_page_area(m, base, end - base);
 737                 KASSERT(vm_page_all_valid(m), ("%s: page %p is invalid",
 738                     __func__, m));
 739                 vm_page_set_dirty(m);
 740                 vm_page_xunbusy(m);
 741         }
 742
 743         return (0);
 744 }
 745
 746 static int
 747 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie)
 748 {
 749         vm_object_t object;
 750         vm_pindex_t nobjsize;
 751         vm_ooffset_t delta;
 752         int base, error;
 753
 754         KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
 755         object = shmfd->shm_object;
 756         VM_OBJECT_ASSERT_WLOCKED(object);
 757         rangelock_cookie_assert(rl_cookie, RA_WLOCKED);
 758         if (length == shmfd->shm_size)
 759                 return (0);
 760         nobjsize = OFF_TO_IDX(length + PAGE_MASK);
 761
 762         /* Are we shrinking?  If so, trim the end. */
 763         if (length < shmfd->shm_size) {
 764                 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0)
 765                         return (EPERM);
 766
 767                 /*
 768                  * Disallow any requests to shrink the size if this
 769                  * object is mapped into the kernel.
 770                  */
 771                 if (shmfd->shm_kmappings > 0)
 772                         return (EBUSY);
 773
 774                 /*
 775                  * Zero the truncated part of the last page.
 776                  */
 777                 base = length & PAGE_MASK;
 778                 if (base != 0) {
 779                         error = shm_partial_page_invalidate(object,
 780                             OFF_TO_IDX(length), base, PAGE_SIZE);
 781                         if (error)
 782                                 return (error);
 783                 }
 784                 delta = IDX_TO_OFF(object->size - nobjsize);
 785
 786                 if (nobjsize < object->size)
 787                         vm_object_page_remove(object, nobjsize, object->size,
 788                             0);
 789
 790                 /* Free the swap accounted for shm */
 791                 swap_release_by_cred(delta, object->cred);
 792                 object->charge -= delta;
 793         } else {
 794                 if ((shmfd->shm_seals & F_SEAL_GROW) != 0)
 795                         return (EPERM);
 796
 797                 /* Try to reserve additional swap space. */
 798                 delta = IDX_TO_OFF(nobjsize - object->size);
 799                 if (!swap_reserve_by_cred(delta, object->cred))
 800                         return (ENOMEM);
 801                 object->charge += delta;
 802         }
 803         shmfd->shm_size = length;
 804         mtx_lock(&shm_timestamp_lock);
 805         vfs_timestamp(&shmfd->shm_ctime);
 806         shmfd->shm_mtime = shmfd->shm_ctime;
 807         mtx_unlock(&shm_timestamp_lock);
 808         object->size = nobjsize;
 809         return (0);
 810 }
 811
 812 static int
 813 shm_dotruncate_largepage(struct shmfd *shmfd, off_t length, void *rl_cookie)
 814 {
 815         vm_object_t object;
 816         vm_page_t m;
 817         vm_pindex_t newobjsz;
 818         vm_pindex_t oldobjsz __unused;
 819         int aflags, error, i, psind, try;
 820
 821         KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
 822         object = shmfd->shm_object;
 823         VM_OBJECT_ASSERT_WLOCKED(object);
 824         rangelock_cookie_assert(rl_cookie, RA_WLOCKED);
 825
 826         oldobjsz = object->size;
 827         newobjsz = OFF_TO_IDX(length);
 828         if (length == shmfd->shm_size)
 829                 return (0);
 830         psind = shmfd->shm_lp_psind;
 831         if (psind == 0 && length != 0)
 832                 return (EINVAL);
 833         if ((length & (pagesizes[psind] - 1)) != 0)
 834                 return (EINVAL);
 835
 836         if (length < shmfd->shm_size) {
 837                 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0)
 838                         return (EPERM);
 839                 if (shmfd->shm_kmappings > 0)
 840                         return (EBUSY);
 841                 return (ENOTSUP);       /* Pages are unmanaged. */
 842 #if 0
 843                 vm_object_page_remove(object, newobjsz, oldobjsz, 0);
 844                 object->size = newobjsz;
 845                 shmfd->shm_size = length;
 846                 return (0);
 847 #endif
 848         }
 849
 850         if ((shmfd->shm_seals & F_SEAL_GROW) != 0)
 851                 return (EPERM);
 852
 853         aflags = VM_ALLOC_NORMAL | VM_ALLOC_ZERO;
 854         if (shmfd->shm_lp_alloc_policy == SHM_LARGEPAGE_ALLOC_NOWAIT)
 855                 aflags |= VM_ALLOC_WAITFAIL;
 856         try = 0;
 857
 858         /*
 859          * Extend shmfd and object, keeping all already fully
 860          * allocated large pages intact even on error, because dropped
 861          * object lock might allowed mapping of them.
 862          */
 863         while (object->size < newobjsz) {
 864                 m = vm_page_alloc_contig(object, object->size, aflags,
 865                     pagesizes[psind] / PAGE_SIZE, 0, ~0,
 866                     pagesizes[psind], 0,
 867                     VM_MEMATTR_DEFAULT);
 868                 if (m == NULL) {
 869                         VM_OBJECT_WUNLOCK(object);
 870                         if (shmfd->shm_lp_alloc_policy ==
 871                             SHM_LARGEPAGE_ALLOC_NOWAIT ||
 872                             (shmfd->shm_lp_alloc_policy ==
 873                             SHM_LARGEPAGE_ALLOC_DEFAULT &&
 874                             try >= largepage_reclaim_tries)) {
 875                                 VM_OBJECT_WLOCK(object);
 876                                 return (ENOMEM);
 877                         }
 878                         error = vm_page_reclaim_contig(aflags,
 879                             pagesizes[psind] / PAGE_SIZE, 0, ~0,
 880                             pagesizes[psind], 0) ? 0 :
 881                             vm_wait_intr(object);
 882                         if (error != 0) {
 883                                 VM_OBJECT_WLOCK(object);
 884                                 return (error);
 885                         }
 886                         try++;
 887                         VM_OBJECT_WLOCK(object);
 888                         continue;
 889                 }
 890                 try = 0;
 891                 for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) {
 892                         if ((m[i].flags & PG_ZERO) == 0)
 893                                 pmap_zero_page(&m[i]);
 894                         vm_page_valid(&m[i]);
 895                         vm_page_xunbusy(&m[i]);
 896                 }
 897                 object->size += OFF_TO_IDX(pagesizes[psind]);
 898                 shmfd->shm_size += pagesizes[psind];
 899                 atomic_add_long(&count_largepages[psind], 1);
 900                 vm_wire_add(atop(pagesizes[psind]));
 901         }
 902         return (0);
 903 }
 904
 905 static int
 906 shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie)
 907 {
 908         int error;
 909
 910         VM_OBJECT_WLOCK(shmfd->shm_object);
 911         error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd,
 912             length, rl_cookie) : shm_dotruncate_locked(shmfd, length,
 913             rl_cookie);
 914         VM_OBJECT_WUNLOCK(shmfd->shm_object);
 915         return (error);
 916 }
 917
 918 int
 919 shm_dotruncate(struct shmfd *shmfd, off_t length)
 920 {
 921         void *rl_cookie;
 922         int error;
 923
 924         rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
 925         error = shm_dotruncate_cookie(shmfd, length, rl_cookie);
 926         shm_rangelock_unlock(shmfd, rl_cookie);
 927         return (error);
 928 }
 929
 930 /*
 931  * shmfd object management including creation and reference counting
 932  * routines.
 933  */
 934 struct shmfd *
 935 shm_alloc(struct ucred *ucred, mode_t mode, bool largepage)
 936 {
 937         struct shmfd *shmfd;
 938         vm_object_t obj;
 939
 940         shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
 941         shmfd->shm_size = 0;
 942         shmfd->shm_uid = ucred->cr_uid;
 943         shmfd->shm_gid = ucred->cr_gid;
 944         shmfd->shm_mode = mode;
 945         if (largepage) {
 946                 shmfd->shm_object = phys_pager_allocate(NULL,
 947                     &shm_largepage_phys_ops, NULL, shmfd->shm_size,
 948                     VM_PROT_DEFAULT, 0, ucred);
 949                 shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT;
 950         } else {
 951                 obj = vm_pager_allocate(shmfd_pager_type, NULL,
 952                     shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred);
 953                 VM_OBJECT_WLOCK(obj);
 954                 obj->un_pager.swp.swp_priv = shmfd;
 955                 VM_OBJECT_WUNLOCK(obj);
 956                 shmfd->shm_object = obj;
 957         }
 958         KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate"));
 959         vfs_timestamp(&shmfd->shm_birthtime);
 960         shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
 961             shmfd->shm_birthtime;
 962         shmfd->shm_ino = alloc_unr64(&shm_ino_unr);
 963         refcount_init(&shmfd->shm_refs, 1);
 964         mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF);
 965         rangelock_init(&shmfd->shm_rl);
 966 #ifdef MAC
 967         mac_posixshm_init(shmfd);
 968         mac_posixshm_create(ucred, shmfd);
 969 #endif
 970
 971         return (shmfd);
 972 }
 973
 974 struct shmfd *
 975 shm_hold(struct shmfd *shmfd)
 976 {
 977
 978         refcount_acquire(&shmfd->shm_refs);
 979         return (shmfd);
 980 }
 981
 982 void
 983 shm_drop(struct shmfd *shmfd)
 984 {
 985         vm_object_t obj;
 986
 987         if (refcount_release(&shmfd->shm_refs)) {
 988 #ifdef MAC
 989                 mac_posixshm_destroy(shmfd);
 990 #endif
 991                 rangelock_destroy(&shmfd->shm_rl);
 992                 mtx_destroy(&shmfd->shm_mtx);
 993                 obj = shmfd->shm_object;
 994                 if (!shm_largepage(shmfd)) {
 995                         VM_OBJECT_WLOCK(obj);
 996                         obj->un_pager.swp.swp_priv = NULL;
 997                         VM_OBJECT_WUNLOCK(obj);
 998                 }
 999                 vm_object_deallocate(obj);
1000                 free(shmfd, M_SHMFD);
1001         }
1002 }
1003
1004 /*
1005  * Determine if the credentials have sufficient permissions for a
1006  * specified combination of FREAD and FWRITE.
1007  */
1008 int
1009 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
1010 {
1011         accmode_t accmode;
1012         int error;
1013
1014         accmode = 0;
1015         if (flags & FREAD)
1016                 accmode |= VREAD;
1017         if (flags & FWRITE)
1018                 accmode |= VWRITE;
1019         mtx_lock(&shm_timestamp_lock);
1020         error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
1021             accmode, ucred);
1022         mtx_unlock(&shm_timestamp_lock);
1023         return (error);
1024 }
1025
1026 static void
1027 shm_init(void *arg)
1028 {
1029         char name[32];
1030         int i;
1031
1032         mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
1033         sx_init(&shm_dict_lock, "shm dictionary");
1034         shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
1035         new_unrhdr64(&shm_ino_unr, 1);
1036         shm_dev_ino = devfs_alloc_cdp_inode();
1037         KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized"));
1038         shmfd_pager_type = vm_pager_alloc_dyn_type(&shm_swap_pager_ops,
1039             OBJT_SWAP);
1040         MPASS(shmfd_pager_type != -1);
1041
1042         for (i = 1; i < MAXPAGESIZES; i++) {
1043                 if (pagesizes[i] == 0)
1044                         break;
1045 #define M       (1024 * 1024)
1046 #define G       (1024 * M)
1047                 if (pagesizes[i] >= G)
1048                         snprintf(name, sizeof(name), "%luG", pagesizes[i] / G);
1049                 else if (pagesizes[i] >= M)
1050                         snprintf(name, sizeof(name), "%luM", pagesizes[i] / M);
1051                 else
1052                         snprintf(name, sizeof(name), "%lu", pagesizes[i]);
1053 #undef G
1054 #undef M
1055                 SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages),
1056                     OID_AUTO, name, CTLFLAG_RD, &count_largepages[i],
1057                     "number of non-transient largepages allocated");
1058         }
1059 }
1060 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL);
1061
1062 /*
1063  * Remove all shared memory objects that belong to a prison.
1064  */
1065 void
1066 shm_remove_prison(struct prison *pr)
1067 {
1068         struct shm_mapping *shmm, *tshmm;
1069         u_long i;
1070
1071         sx_xlock(&shm_dict_lock);
1072         for (i = 0; i < shm_hash + 1; i++) {
1073                 LIST_FOREACH_SAFE(shmm, &shm_dictionary[i], sm_link, tshmm) {
1074                         if (shmm->sm_shmfd->shm_object->cred &&
1075                             shmm->sm_shmfd->shm_object->cred->cr_prison == pr)
1076                                 shm_doremove(shmm);
1077                 }
1078         }
1079         sx_xunlock(&shm_dict_lock);
1080 }
1081
1082 /*
1083  * Dictionary management.  We maintain an in-kernel dictionary to map
1084  * paths to shmfd objects.  We use the FNV hash on the path to store
1085  * the mappings in a hash table.
1086  */
1087 static struct shmfd *
1088 shm_lookup(char *path, Fnv32_t fnv)
1089 {
1090         struct shm_mapping *map;
1091
1092         LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
1093                 if (map->sm_fnv != fnv)
1094                         continue;
1095                 if (strcmp(map->sm_path, path) == 0)
1096                         return (map->sm_shmfd);
1097         }
1098
1099         return (NULL);
1100 }
1101
1102 static void
1103 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
1104 {
1105         struct shm_mapping *map;
1106
1107         map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
1108         map->sm_path = path;
1109         map->sm_fnv = fnv;
1110         map->sm_shmfd = shm_hold(shmfd);
1111         shmfd->shm_path = path;
1112         LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
1113 }
1114
1115 static int
1116 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
1117 {
1118         struct shm_mapping *map;
1119         int error;
1120
1121         LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
1122                 if (map->sm_fnv != fnv)
1123                         continue;
1124                 if (strcmp(map->sm_path, path) == 0) {
1125 #ifdef MAC
1126                         error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
1127                         if (error)
1128                                 return (error);
1129 #endif
1130                         error = shm_access(map->sm_shmfd, ucred,
1131                             FREAD | FWRITE);
1132                         if (error)
1133                                 return (error);
1134                         shm_doremove(map);
1135                         return (0);
1136                 }
1137         }
1138
1139         return (ENOENT);
1140 }
1141
1142 static void
1143 shm_doremove(struct shm_mapping *map)
1144 {
1145         map->sm_shmfd->shm_path = NULL;
1146         LIST_REMOVE(map, sm_link);
1147         shm_drop(map->sm_shmfd);
1148         free(map->sm_path, M_SHMFD);
1149         free(map, M_SHMFD);
1150 }
1151
1152 int
1153 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode,
1154     int shmflags, struct filecaps *fcaps, const char *name __unused)
1155 {
1156         struct pwddesc *pdp;
1157         struct shmfd *shmfd;
1158         struct file *fp;
1159         char *path;
1160         void *rl_cookie;
1161         Fnv32_t fnv;
1162         mode_t cmode;
1163         int error, fd, initial_seals;
1164         bool largepage;
1165
1166         if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE |
1167             SHM_LARGEPAGE)) != 0)
1168                 return (EINVAL);
1169
1170         initial_seals = F_SEAL_SEAL;
1171         if ((shmflags & SHM_ALLOW_SEALING) != 0)
1172                 initial_seals &= ~F_SEAL_SEAL;
1173
1174 #ifdef CAPABILITY_MODE
1175         /*
1176          * shm_open(2) is only allowed for anonymous objects.
1177          */
1178         if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON))
1179                 return (ECAPMODE);
1180 #endif
1181
1182         AUDIT_ARG_FFLAGS(flags);
1183         AUDIT_ARG_MODE(mode);
1184
1185         if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR)
1186                 return (EINVAL);
1187
1188         if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0)
1189                 return (EINVAL);
1190
1191         largepage = (shmflags & SHM_LARGEPAGE) != 0;
1192         if (largepage && !PMAP_HAS_LARGEPAGES)
1193                 return (ENOTTY);
1194
1195         /*
1196          * Currently only F_SEAL_SEAL may be set when creating or opening shmfd.
1197          * If the decision is made later to allow additional seals, care must be
1198          * taken below to ensure that the seals are properly set if the shmfd
1199          * already existed -- this currently assumes that only F_SEAL_SEAL can
1200          * be set and doesn't take further precautions to ensure the validity of
1201          * the seals being added with respect to current mappings.
1202          */
1203         if ((initial_seals & ~F_SEAL_SEAL) != 0)
1204                 return (EINVAL);
1205
1206         pdp = td->td_proc->p_pd;
1207         cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS;
1208
1209         /*
1210          * shm_open(2) created shm should always have O_CLOEXEC set, as mandated
1211          * by POSIX.  We allow it to be unset here so that an in-kernel
1212          * interface may be written as a thin layer around shm, optionally not
1213          * setting CLOEXEC.  For shm_open(2), O_CLOEXEC is set unconditionally
1214          * in sys_shm_open() to keep this implementation compliant.
1215          */
1216         error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps);
1217         if (error)
1218                 return (error);
1219
1220         /* A SHM_ANON path pointer creates an anonymous object. */
1221         if (userpath == SHM_ANON) {
1222                 /* A read-only anonymous object is pointless. */
1223                 if ((flags & O_ACCMODE) == O_RDONLY) {
1224                         fdclose(td, fp, fd);
1225                         fdrop(fp, td);
1226                         return (EINVAL);
1227                 }
1228                 shmfd = shm_alloc(td->td_ucred, cmode, largepage);
1229                 shmfd->shm_seals = initial_seals;
1230                 shmfd->shm_flags = shmflags;
1231         } else {
1232                 error = shm_copyin_path(td, userpath, &path);
1233                 if (error != 0) {
1234                         fdclose(td, fp, fd);
1235                         fdrop(fp, td);
1236                         return (error);
1237                 }
1238
1239                 AUDIT_ARG_UPATH1_CANON(path);
1240                 fnv = fnv_32_str(path, FNV1_32_INIT);
1241                 sx_xlock(&shm_dict_lock);
1242                 shmfd = shm_lookup(path, fnv);
1243                 if (shmfd == NULL) {
1244                         /* Object does not yet exist, create it if requested. */
1245                         if (flags & O_CREAT) {
1246 #ifdef MAC
1247                                 error = mac_posixshm_check_create(td->td_ucred,
1248                                     path);
1249                                 if (error == 0) {
1250 #endif
1251                                         shmfd = shm_alloc(td->td_ucred, cmode,
1252                                             largepage);
1253                                         shmfd->shm_seals = initial_seals;
1254                                         shmfd->shm_flags = shmflags;
1255                                         shm_insert(path, fnv, shmfd);
1256 #ifdef MAC
1257                                 }
1258 #endif
1259                         } else {
1260                                 free(path, M_SHMFD);
1261                                 error = ENOENT;
1262                         }
1263                 } else {
1264                         rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
1265
1266                         /*
1267                          * kern_shm_open() likely shouldn't ever error out on
1268                          * trying to set a seal that already exists, unlike
1269                          * F_ADD_SEALS.  This would break terribly as
1270                          * shm_open(2) actually sets F_SEAL_SEAL to maintain
1271                          * historical behavior where the underlying file could
1272                          * not be sealed.
1273                          */
1274                         initial_seals &= ~shmfd->shm_seals;
1275
1276                         /*
1277                          * Object already exists, obtain a new
1278                          * reference if requested and permitted.
1279                          */
1280                         free(path, M_SHMFD);
1281
1282                         /*
1283                          * initial_seals can't set additional seals if we've
1284                          * already been set F_SEAL_SEAL.  If F_SEAL_SEAL is set,
1285                          * then we've already removed that one from
1286                          * initial_seals.  This is currently redundant as we
1287                          * only allow setting F_SEAL_SEAL at creation time, but
1288                          * it's cheap to check and decreases the effort required
1289                          * to allow additional seals.
1290                          */
1291                         if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 &&
1292                             initial_seals != 0)
1293                                 error = EPERM;
1294                         else if ((flags & (O_CREAT | O_EXCL)) ==
1295                             (O_CREAT | O_EXCL))
1296                                 error = EEXIST;
1297                         else if (shmflags != 0 && shmflags != shmfd->shm_flags)
1298                                 error = EINVAL;
1299                         else {
1300 #ifdef MAC
1301                                 error = mac_posixshm_check_open(td->td_ucred,
1302                                     shmfd, FFLAGS(flags & O_ACCMODE));
1303                                 if (error == 0)
1304 #endif
1305                                 error = shm_access(shmfd, td->td_ucred,
1306                                     FFLAGS(flags & O_ACCMODE));
1307                         }
1308
1309                         /*
1310                          * Truncate the file back to zero length if
1311                          * O_TRUNC was specified and the object was
1312                          * opened with read/write.
1313                          */
1314                         if (error == 0 &&
1315                             (flags & (O_ACCMODE | O_TRUNC)) ==
1316                             (O_RDWR | O_TRUNC)) {
1317                                 VM_OBJECT_WLOCK(shmfd->shm_object);
1318 #ifdef MAC
1319                                 error = mac_posixshm_check_truncate(
1320                                         td->td_ucred, fp->f_cred, shmfd);
1321                                 if (error == 0)
1322 #endif
1323                                         error = shm_dotruncate_locked(shmfd, 0,
1324                                             rl_cookie);
1325                                 VM_OBJECT_WUNLOCK(shmfd->shm_object);
1326                         }
1327                         if (error == 0) {
1328                                 /*
1329                                  * Currently we only allow F_SEAL_SEAL to be
1330                                  * set initially.  As noted above, this would
1331                                  * need to be reworked should that change.
1332                                  */
1333                                 shmfd->shm_seals |= initial_seals;
1334                                 shm_hold(shmfd);
1335                         }
1336                         shm_rangelock_unlock(shmfd, rl_cookie);
1337                 }
1338                 sx_xunlock(&shm_dict_lock);
1339
1340                 if (error) {
1341                         fdclose(td, fp, fd);
1342                         fdrop(fp, td);
1343                         return (error);
1344                 }
1345         }
1346
1347         finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
1348
1349         td->td_retval[0] = fd;
1350         fdrop(fp, td);
1351
1352         return (0);
1353 }
1354
1355 /* System calls. */
1356 #ifdef COMPAT_FREEBSD12
1357 int
1358 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap)
1359 {
1360
1361         return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC,
1362             uap->mode, NULL));
1363 }
1364 #endif
1365
1366 int
1367 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
1368 {
1369         char *path;
1370         Fnv32_t fnv;
1371         int error;
1372
1373         error = shm_copyin_path(td, uap->path, &path);
1374         if (error != 0)
1375                 return (error);
1376
1377         AUDIT_ARG_UPATH1_CANON(path);
1378         fnv = fnv_32_str(path, FNV1_32_INIT);
1379         sx_xlock(&shm_dict_lock);
1380         error = shm_remove(path, fnv, td->td_ucred);
1381         sx_xunlock(&shm_dict_lock);
1382         free(path, M_SHMFD);
1383
1384         return (error);
1385 }
1386
1387 int
1388 sys_shm_rename(struct thread *td, struct shm_rename_args *uap)
1389 {
1390         char *path_from = NULL, *path_to = NULL;
1391         Fnv32_t fnv_from, fnv_to;
1392         struct shmfd *fd_from;
1393         struct shmfd *fd_to;
1394         int error;
1395         int flags;
1396
1397         flags = uap->flags;
1398         AUDIT_ARG_FFLAGS(flags);
1399
1400         /*
1401          * Make sure the user passed only valid flags.
1402          * If you add a new flag, please add a new term here.
1403          */
1404         if ((flags & ~(
1405             SHM_RENAME_NOREPLACE |
1406             SHM_RENAME_EXCHANGE
1407             )) != 0) {
1408                 error = EINVAL;
1409                 goto out;
1410         }
1411
1412         /*
1413          * EXCHANGE and NOREPLACE don't quite make sense together. Let's
1414          * force the user to choose one or the other.
1415          */
1416         if ((flags & SHM_RENAME_NOREPLACE) != 0 &&
1417             (flags & SHM_RENAME_EXCHANGE) != 0) {
1418                 error = EINVAL;
1419                 goto out;
1420         }
1421
1422         /* Renaming to or from anonymous makes no sense */
1423         if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) {
1424                 error = EINVAL;
1425                 goto out;
1426         }
1427
1428         error = shm_copyin_path(td, uap->path_from, &path_from);
1429         if (error != 0)
1430                 goto out;
1431
1432         error = shm_copyin_path(td, uap->path_to, &path_to);
1433         if (error != 0)
1434                 goto out;
1435
1436         AUDIT_ARG_UPATH1_CANON(path_from);
1437         AUDIT_ARG_UPATH2_CANON(path_to);
1438
1439         /* Rename with from/to equal is a no-op */
1440         if (strcmp(path_from, path_to) == 0)
1441                 goto out;
1442
1443         fnv_from = fnv_32_str(path_from, FNV1_32_INIT);
1444         fnv_to = fnv_32_str(path_to, FNV1_32_INIT);
1445
1446         sx_xlock(&shm_dict_lock);
1447
1448         fd_from = shm_lookup(path_from, fnv_from);
1449         if (fd_from == NULL) {
1450                 error = ENOENT;
1451                 goto out_locked;
1452         }
1453
1454         fd_to = shm_lookup(path_to, fnv_to);
1455         if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) {
1456                 error = EEXIST;
1457                 goto out_locked;
1458         }
1459
1460         /*
1461          * Unconditionally prevents shm_remove from invalidating the 'from'
1462          * shm's state.
1463          */
1464         shm_hold(fd_from);
1465         error = shm_remove(path_from, fnv_from, td->td_ucred);
1466
1467         /*
1468          * One of my assumptions failed if ENOENT (e.g. locking didn't
1469          * protect us)
1470          */
1471         KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s",
1472             path_from));
1473         if (error != 0) {
1474                 shm_drop(fd_from);
1475                 goto out_locked;
1476         }
1477
1478         /*
1479          * If we are exchanging, we need to ensure the shm_remove below
1480          * doesn't invalidate the dest shm's state.
1481          */
1482         if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL)
1483                 shm_hold(fd_to);
1484
1485         /*
1486          * NOTE: if path_to is not already in the hash, c'est la vie;
1487          * it simply means we have nothing already at path_to to unlink.
1488          * That is the ENOENT case.
1489          *
1490          * If we somehow don't have access to unlink this guy, but
1491          * did for the shm at path_from, then relink the shm to path_from
1492          * and abort with EACCES.
1493          *
1494          * All other errors: that is weird; let's relink and abort the
1495          * operation.
1496          */
1497         error = shm_remove(path_to, fnv_to, td->td_ucred);
1498         if (error != 0 && error != ENOENT) {
1499                 shm_insert(path_from, fnv_from, fd_from);
1500                 shm_drop(fd_from);
1501                 /* Don't free path_from now, since the hash references it */
1502                 path_from = NULL;
1503                 goto out_locked;
1504         }
1505
1506         error = 0;
1507
1508         shm_insert(path_to, fnv_to, fd_from);
1509
1510         /* Don't free path_to now, since the hash references it */
1511         path_to = NULL;
1512
1513         /* We kept a ref when we removed, and incremented again in insert */
1514         shm_drop(fd_from);
1515         KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n",
1516             fd_from->shm_refs));
1517
1518         if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) {
1519                 shm_insert(path_from, fnv_from, fd_to);
1520                 path_from = NULL;
1521                 shm_drop(fd_to);
1522                 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n",
1523                     fd_to->shm_refs));
1524         }
1525
1526 out_locked:
1527         sx_xunlock(&shm_dict_lock);
1528
1529 out:
1530         free(path_from, M_SHMFD);
1531         free(path_to, M_SHMFD);
1532         return (error);
1533 }
1534
1535 static int
1536 shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr,
1537     vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags,
1538     vm_ooffset_t foff, struct thread *td)
1539 {
1540         struct vmspace *vms;
1541         vm_map_entry_t next_entry, prev_entry;
1542         vm_offset_t align, mask, maxaddr;
1543         int docow, error, rv, try;
1544         bool curmap;
1545
1546         if (shmfd->shm_lp_psind == 0)
1547                 return (EINVAL);
1548
1549         /* MAP_PRIVATE is disabled */
1550         if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL |
1551             MAP_NOCORE | MAP_32BIT | MAP_ALIGNMENT_MASK)) != 0)
1552                 return (EINVAL);
1553
1554         vms = td->td_proc->p_vmspace;
1555         curmap = map == &vms->vm_map;
1556         if (curmap) {
1557                 error = kern_mmap_racct_check(td, map, size);
1558                 if (error != 0)
1559                         return (error);
1560         }
1561
1562         docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT;
1563         docow |= MAP_INHERIT_SHARE;
1564         if ((flags & MAP_NOCORE) != 0)
1565                 docow |= MAP_DISABLE_COREDUMP;
1566
1567         mask = pagesizes[shmfd->shm_lp_psind] - 1;
1568         if ((foff & mask) != 0)
1569                 return (EINVAL);
1570         maxaddr = vm_map_max(map);
1571         if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR)
1572                 maxaddr = MAP_32BIT_MAX_ADDR;
1573         if (size == 0 || (size & mask) != 0 ||
1574             (*addr != 0 && ((*addr & mask) != 0 ||
1575             *addr + size < *addr || *addr + size > maxaddr)))
1576                 return (EINVAL);
1577
1578         align = flags & MAP_ALIGNMENT_MASK;
1579         if (align == 0) {
1580                 align = pagesizes[shmfd->shm_lp_psind];
1581         } else if (align == MAP_ALIGNED_SUPER) {
1582                 if (shmfd->shm_lp_psind != 1)
1583                         return (EINVAL);
1584                 align = pagesizes[1];
1585         } else {
1586                 align >>= MAP_ALIGNMENT_SHIFT;
1587                 align = 1ULL << align;
1588                 /* Also handles overflow. */
1589                 if (align < pagesizes[shmfd->shm_lp_psind])
1590                         return (EINVAL);
1591         }
1592
1593         vm_map_lock(map);
1594         if ((flags & MAP_FIXED) == 0) {
1595                 try = 1;
1596                 if (curmap && (*addr == 0 ||
1597                     (*addr >= round_page((vm_offset_t)vms->vm_taddr) &&
1598                     *addr < round_page((vm_offset_t)vms->vm_daddr +
1599                     lim_max(td, RLIMIT_DATA))))) {
1600                         *addr = roundup2((vm_offset_t)vms->vm_daddr +
1601                             lim_max(td, RLIMIT_DATA),
1602                             pagesizes[shmfd->shm_lp_psind]);
1603                 }
1604 again:
1605                 rv = vm_map_find_aligned(map, addr, size, maxaddr, align);
1606                 if (rv != KERN_SUCCESS) {
1607                         if (try == 1) {
1608                                 try = 2;
1609                                 *addr = vm_map_min(map);
1610                                 if ((*addr & mask) != 0)
1611                                         *addr = (*addr + mask) & mask;
1612                                 goto again;
1613                         }
1614                         goto fail1;
1615                 }
1616         } else if ((flags & MAP_EXCL) == 0) {
1617                 rv = vm_map_delete(map, *addr, *addr + size);
1618                 if (rv != KERN_SUCCESS)
1619                         goto fail1;
1620         } else {
1621                 error = ENOSPC;
1622                 if (vm_map_lookup_entry(map, *addr, &prev_entry))
1623                         goto fail;
1624                 next_entry = vm_map_entry_succ(prev_entry);
1625                 if (next_entry->start < *addr + size)
1626                         goto fail;
1627         }
1628
1629         rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size,
1630             prot, max_prot, docow);
1631 fail1:
1632         error = vm_mmap_to_errno(rv);
1633 fail:
1634         vm_map_unlock(map);
1635         return (error);
1636 }
1637
1638 static int
1639 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize,
1640     vm_prot_t prot, vm_prot_t cap_maxprot, int flags,
1641     vm_ooffset_t foff, struct thread *td)
1642 {
1643         struct shmfd *shmfd;
1644         vm_prot_t maxprot;
1645         int error;
1646         bool writecnt;
1647         void *rl_cookie;
1648
1649         shmfd = fp->f_data;
1650         maxprot = VM_PROT_NONE;
1651
1652         rl_cookie = shm_rangelock_rlock(shmfd, 0, objsize);
1653         /* FREAD should always be set. */
1654         if ((fp->f_flag & FREAD) != 0)
1655                 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ;
1656
1657         /*
1658          * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared
1659          * mapping with a write seal applied.  Private mappings are always
1660          * writeable.
1661          */
1662         if ((flags & MAP_SHARED) == 0) {
1663                 cap_maxprot |= VM_PROT_WRITE;
1664                 maxprot |= VM_PROT_WRITE;
1665                 writecnt = false;
1666         } else {
1667                 if ((fp->f_flag & FWRITE) != 0 &&
1668                     (shmfd->shm_seals & F_SEAL_WRITE) == 0)
1669                         maxprot |= VM_PROT_WRITE;
1670
1671                 /*
1672                  * Any mappings from a writable descriptor may be upgraded to
1673                  * VM_PROT_WRITE with mprotect(2), unless a write-seal was
1674                  * applied between the open and subsequent mmap(2).  We want to
1675                  * reject application of a write seal as long as any such
1676                  * mapping exists so that the seal cannot be trivially bypassed.
1677                  */
1678                 writecnt = (maxprot & VM_PROT_WRITE) != 0;
1679                 if (!writecnt && (prot & VM_PROT_WRITE) != 0) {
1680                         error = EACCES;
1681                         goto out;
1682                 }
1683         }
1684         maxprot &= cap_maxprot;
1685
1686         /* See comment in vn_mmap(). */
1687         if (
1688 #ifdef _LP64
1689             objsize > OFF_MAX ||
1690 #endif
1691             foff > OFF_MAX - objsize) {
1692                 error = EINVAL;
1693                 goto out;
1694         }
1695
1696 #ifdef MAC
1697         error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags);
1698         if (error != 0)
1699                 goto out;
1700 #endif
1701
1702         mtx_lock(&shm_timestamp_lock);
1703         vfs_timestamp(&shmfd->shm_atime);
1704         mtx_unlock(&shm_timestamp_lock);
1705         vm_object_reference(shmfd->shm_object);
1706
1707         if (shm_largepage(shmfd)) {
1708                 writecnt = false;
1709                 error = shm_mmap_large(shmfd, map, addr, objsize, prot,
1710                     maxprot, flags, foff, td);
1711         } else {
1712                 if (writecnt) {
1713                         vm_pager_update_writecount(shmfd->shm_object, 0,
1714                             objsize);
1715                 }
1716                 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags,
1717                     shmfd->shm_object, foff, writecnt, td);
1718         }
1719         if (error != 0) {
1720                 if (writecnt)
1721                         vm_pager_release_writecount(shmfd->shm_object, 0,
1722                             objsize);
1723                 vm_object_deallocate(shmfd->shm_object);
1724         }
1725 out:
1726         shm_rangelock_unlock(shmfd, rl_cookie);
1727         return (error);
1728 }
1729
1730 static int
1731 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
1732     struct thread *td)
1733 {
1734         struct shmfd *shmfd;
1735         int error;
1736
1737         error = 0;
1738         shmfd = fp->f_data;
1739         mtx_lock(&shm_timestamp_lock);
1740         /*
1741          * SUSv4 says that x bits of permission need not be affected.
1742          * Be consistent with our shm_open there.
1743          */
1744 #ifdef MAC
1745         error = mac_posixshm_check_setmode(active_cred, shmfd, mode);
1746         if (error != 0)
1747                 goto out;
1748 #endif
1749         error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
1750             VADMIN, active_cred);
1751         if (error != 0)
1752                 goto out;
1753         shmfd->shm_mode = mode & ACCESSPERMS;
1754 out:
1755         mtx_unlock(&shm_timestamp_lock);
1756         return (error);
1757 }
1758
1759 static int
1760 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
1761     struct thread *td)
1762 {
1763         struct shmfd *shmfd;
1764         int error;
1765
1766         error = 0;
1767         shmfd = fp->f_data;
1768         mtx_lock(&shm_timestamp_lock);
1769 #ifdef MAC
1770         error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid);
1771         if (error != 0)
1772                 goto out;
1773 #endif
1774         if (uid == (uid_t)-1)
1775                 uid = shmfd->shm_uid;
1776         if (gid == (gid_t)-1)
1777                  gid = shmfd->shm_gid;
1778         if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) ||
1779             (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) &&
1780             (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN)))
1781                 goto out;
1782         shmfd->shm_uid = uid;
1783         shmfd->shm_gid = gid;
1784 out:
1785         mtx_unlock(&shm_timestamp_lock);
1786         return (error);
1787 }
1788
1789 /*
1790  * Helper routines to allow the backing object of a shared memory file
1791  * descriptor to be mapped in the kernel.
1792  */
1793 int
1794 shm_map(struct file *fp, size_t size, off_t offset, void **memp)
1795 {
1796         struct shmfd *shmfd;
1797         vm_offset_t kva, ofs;
1798         vm_object_t obj;
1799         int rv;
1800
1801         if (fp->f_type != DTYPE_SHM)
1802                 return (EINVAL);
1803         shmfd = fp->f_data;
1804         obj = shmfd->shm_object;
1805         VM_OBJECT_WLOCK(obj);
1806         /*
1807          * XXXRW: This validation is probably insufficient, and subject to
1808          * sign errors.  It should be fixed.
1809          */
1810         if (offset >= shmfd->shm_size ||
1811             offset + size > round_page(shmfd->shm_size)) {
1812                 VM_OBJECT_WUNLOCK(obj);
1813                 return (EINVAL);
1814         }
1815
1816         shmfd->shm_kmappings++;
1817         vm_object_reference_locked(obj);
1818         VM_OBJECT_WUNLOCK(obj);
1819
1820         /* Map the object into the kernel_map and wire it. */
1821         kva = vm_map_min(kernel_map);
1822         ofs = offset & PAGE_MASK;
1823         offset = trunc_page(offset);
1824         size = round_page(size + ofs);
1825         rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0,
1826             VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE,
1827             VM_PROT_READ | VM_PROT_WRITE, 0);
1828         if (rv == KERN_SUCCESS) {
1829                 rv = vm_map_wire(kernel_map, kva, kva + size,
1830                     VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
1831                 if (rv == KERN_SUCCESS) {
1832                         *memp = (void *)(kva + ofs);
1833                         return (0);
1834                 }
1835                 vm_map_remove(kernel_map, kva, kva + size);
1836         } else
1837                 vm_object_deallocate(obj);
1838
1839         /* On failure, drop our mapping reference. */
1840         VM_OBJECT_WLOCK(obj);
1841         shmfd->shm_kmappings--;
1842         VM_OBJECT_WUNLOCK(obj);
1843
1844         return (vm_mmap_to_errno(rv));
1845 }
1846
1847 /*
1848  * We require the caller to unmap the entire entry.  This allows us to
1849  * safely decrement shm_kmappings when a mapping is removed.
1850  */
1851 int
1852 shm_unmap(struct file *fp, void *mem, size_t size)
1853 {
1854         struct shmfd *shmfd;
1855         vm_map_entry_t entry;
1856         vm_offset_t kva, ofs;
1857         vm_object_t obj;
1858         vm_pindex_t pindex;
1859         vm_prot_t prot;
1860         boolean_t wired;
1861         vm_map_t map;
1862         int rv;
1863
1864         if (fp->f_type != DTYPE_SHM)
1865                 return (EINVAL);
1866         shmfd = fp->f_data;
1867         kva = (vm_offset_t)mem;
1868         ofs = kva & PAGE_MASK;
1869         kva = trunc_page(kva);
1870         size = round_page(size + ofs);
1871         map = kernel_map;
1872         rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry,
1873             &obj, &pindex, &prot, &wired);
1874         if (rv != KERN_SUCCESS)
1875                 return (EINVAL);
1876         if (entry->start != kva || entry->end != kva + size) {
1877                 vm_map_lookup_done(map, entry);
1878                 return (EINVAL);
1879         }
1880         vm_map_lookup_done(map, entry);
1881         if (obj != shmfd->shm_object)
1882                 return (EINVAL);
1883         vm_map_remove(map, kva, kva + size);
1884         VM_OBJECT_WLOCK(obj);
1885         KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped"));
1886         shmfd->shm_kmappings--;
1887         VM_OBJECT_WUNLOCK(obj);
1888         return (0);
1889 }
1890
1891 static int
1892 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list)
1893 {
1894         const char *path, *pr_path;
1895         size_t pr_pathlen;
1896         bool visible;
1897
1898         sx_assert(&shm_dict_lock, SA_LOCKED);
1899         kif->kf_type = KF_TYPE_SHM;
1900         kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode;
1901         kif->kf_un.kf_file.kf_file_size = shmfd->shm_size;
1902         if (shmfd->shm_path != NULL) {
1903                 if (shmfd->shm_path != NULL) {
1904                         path = shmfd->shm_path;
1905                         pr_path = curthread->td_ucred->cr_prison->pr_path;
1906                         if (strcmp(pr_path, "/") != 0) {
1907                                 /* Return the jail-rooted pathname. */
1908                                 pr_pathlen = strlen(pr_path);
1909                                 visible = strncmp(path, pr_path, pr_pathlen)
1910                                     == 0 && path[pr_pathlen] == '/';
1911                                 if (list && !visible)
1912                                         return (EPERM);
1913                                 if (visible)
1914                                         path += pr_pathlen;
1915                         }
1916                         strlcpy(kif->kf_path, path, sizeof(kif->kf_path));
1917                 }
1918         }
1919         return (0);
1920 }
1921
1922 static int
1923 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif,
1924     struct filedesc *fdp __unused)
1925 {
1926         int res;
1927
1928         sx_slock(&shm_dict_lock);
1929         res = shm_fill_kinfo_locked(fp->f_data, kif, false);
1930         sx_sunlock(&shm_dict_lock);
1931         return (res);
1932 }
1933
1934 static int
1935 shm_add_seals(struct file *fp, int seals)
1936 {
1937         struct shmfd *shmfd;
1938         void *rl_cookie;
1939         vm_ooffset_t writemappings;
1940         int error, nseals;
1941
1942         error = 0;
1943         shmfd = fp->f_data;
1944         rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
1945
1946         /* Even already-set seals should result in EPERM. */
1947         if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) {
1948                 error = EPERM;
1949                 goto out;
1950         }
1951         nseals = seals & ~shmfd->shm_seals;
1952         if ((nseals & F_SEAL_WRITE) != 0) {
1953                 if (shm_largepage(shmfd)) {
1954                         error = ENOTSUP;
1955                         goto out;
1956                 }
1957
1958                 /*
1959                  * The rangelock above prevents writable mappings from being
1960                  * added after we've started applying seals.  The RLOCK here
1961                  * is to avoid torn reads on ILP32 arches as unmapping/reducing
1962                  * writemappings will be done without a rangelock.
1963                  */
1964                 VM_OBJECT_RLOCK(shmfd->shm_object);
1965                 writemappings = shmfd->shm_object->un_pager.swp.writemappings;
1966                 VM_OBJECT_RUNLOCK(shmfd->shm_object);
1967                 /* kmappings are also writable */
1968                 if (writemappings > 0) {
1969                         error = EBUSY;
1970                         goto out;
1971                 }
1972         }
1973         shmfd->shm_seals |= nseals;
1974 out:
1975         shm_rangelock_unlock(shmfd, rl_cookie);
1976         return (error);
1977 }
1978
1979 static int
1980 shm_get_seals(struct file *fp, int *seals)
1981 {
1982         struct shmfd *shmfd;
1983
1984         shmfd = fp->f_data;
1985         *seals = shmfd->shm_seals;
1986         return (0);
1987 }
1988
1989 static int
1990 shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t *length, int flags)
1991 {
1992         vm_object_t object;
1993         vm_pindex_t pistart, pi, piend;
1994         vm_ooffset_t off, len;
1995         int startofs, endofs, end;
1996         int error;
1997
1998         off = *offset;
1999         len = *length;
2000         KASSERT(off + len <= (vm_ooffset_t)OFF_MAX, ("off + len overflows"));
2001         if (off + len > shmfd->shm_size)
2002                 len = shmfd->shm_size - off;
2003         object = shmfd->shm_object;
2004         startofs = off & PAGE_MASK;
2005         endofs = (off + len) & PAGE_MASK;
2006         pistart = OFF_TO_IDX(off);
2007         piend = OFF_TO_IDX(off + len);
2008         pi = OFF_TO_IDX(off + PAGE_MASK);
2009         error = 0;
2010
2011         /* Handle the case when offset is on or beyond shm size. */
2012         if ((off_t)len <= 0) {
2013                 *length = 0;
2014                 return (0);
2015         }
2016
2017         VM_OBJECT_WLOCK(object);
2018
2019         if (startofs != 0) {
2020                 end = pistart != piend ? PAGE_SIZE : endofs;
2021                 error = shm_partial_page_invalidate(object, pistart, startofs,
2022                     end);
2023                 if (error)
2024                         goto out;
2025                 off += end - startofs;
2026                 len -= end - startofs;
2027         }
2028
2029         if (pi < piend) {
2030                 vm_object_page_remove(object, pi, piend, 0);
2031                 off += IDX_TO_OFF(piend - pi);
2032                 len -= IDX_TO_OFF(piend - pi);
2033         }
2034
2035         if (endofs != 0 && pistart != piend) {
2036                 error = shm_partial_page_invalidate(object, piend, 0, endofs);
2037                 if (error)
2038                         goto out;
2039                 off += endofs;
2040                 len -= endofs;
2041         }
2042
2043 out:
2044         VM_OBJECT_WUNLOCK(shmfd->shm_object);
2045         *offset = off;
2046         *length = len;
2047         return (error);
2048 }
2049
2050 static int
2051 shm_fspacectl(struct file *fp, int cmd, off_t *offset, off_t *length, int flags,
2052     struct ucred *active_cred, struct thread *td)
2053 {
2054         void *rl_cookie;
2055         struct shmfd *shmfd;
2056         off_t off, len;
2057         int error;
2058
2059         KASSERT(cmd == SPACECTL_DEALLOC, ("shm_fspacectl: Invalid cmd"));
2060         KASSERT((flags & ~SPACECTL_F_SUPPORTED) == 0,
2061             ("shm_fspacectl: non-zero flags"));
2062         KASSERT(*offset >= 0 && *length > 0 && *length <= OFF_MAX - *offset,
2063             ("shm_fspacectl: offset/length overflow or underflow"));
2064         error = EINVAL;
2065         shmfd = fp->f_data;
2066         off = *offset;
2067         len = *length;
2068
2069         rl_cookie = shm_rangelock_wlock(shmfd, off, off + len);
2070         switch (cmd) {
2071         case SPACECTL_DEALLOC:
2072                 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) {
2073                         error = EPERM;
2074                         break;
2075                 }
2076                 error = shm_deallocate(shmfd, &off, &len, flags);
2077                 *offset = off;
2078                 *length = len;
2079                 break;
2080         default:
2081                 __assert_unreachable();
2082         }
2083         shm_rangelock_unlock(shmfd, rl_cookie);
2084         return (error);
2085 }
2086
2087
2088 static int
2089 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td)
2090 {
2091         void *rl_cookie;
2092         struct shmfd *shmfd;
2093         size_t size;
2094         int error;
2095
2096         /* This assumes that the caller already checked for overflow. */
2097         error = 0;
2098         shmfd = fp->f_data;
2099         size = offset + len;
2100
2101         /*
2102          * Just grab the rangelock for the range that we may be attempting to
2103          * grow, rather than blocking read/write for regions we won't be
2104          * touching while this (potential) resize is in progress.  Other
2105          * attempts to resize the shmfd will have to take a write lock from 0 to
2106          * OFF_MAX, so this being potentially beyond the current usable range of
2107          * the shmfd is not necessarily a concern.  If other mechanisms are
2108          * added to grow a shmfd, this may need to be re-evaluated.
2109          */
2110         rl_cookie = shm_rangelock_wlock(shmfd, offset, size);
2111         if (size > shmfd->shm_size)
2112                 error = shm_dotruncate_cookie(shmfd, size, rl_cookie);
2113         shm_rangelock_unlock(shmfd, rl_cookie);
2114         /* Translate to posix_fallocate(2) return value as needed. */
2115         if (error == ENOMEM)
2116                 error = ENOSPC;
2117         return (error);
2118 }
2119
2120 static int
2121 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS)
2122 {
2123         struct shm_mapping *shmm;
2124         struct sbuf sb;
2125         struct kinfo_file kif;
2126         u_long i;
2127         int error, error2;
2128
2129         sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req);
2130         sbuf_clear_flags(&sb, SBUF_INCLUDENUL);
2131         error = 0;
2132         sx_slock(&shm_dict_lock);
2133         for (i = 0; i < shm_hash + 1; i++) {
2134                 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) {
2135                         error = shm_fill_kinfo_locked(shmm->sm_shmfd,
2136                             &kif, true);
2137                         if (error == EPERM) {
2138                                 error = 0;
2139                                 continue;
2140                         }
2141                         if (error != 0)
2142                                 break;
2143                         pack_kinfo(&kif);
2144                         error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ?
2145                             0 : ENOMEM;
2146                         if (error != 0)
2147                                 break;
2148                 }
2149         }
2150         sx_sunlock(&shm_dict_lock);
2151         error2 = sbuf_finish(&sb);
2152         sbuf_delete(&sb);
2153         return (error != 0 ? error : error2);
2154 }
2155
2156 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list,
2157     CTLFLAG_RD | CTLFLAG_PRISON | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE,
2158     NULL, 0, sysctl_posix_shm_list, "",
2159     "POSIX SHM list");
2160
2161 int
2162 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode,
2163     struct filecaps *caps)
2164 {
2165
2166         return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL));
2167 }
2168
2169 /*
2170  * This version of the shm_open() interface leaves CLOEXEC behavior up to the
2171  * caller, and libc will enforce it for the traditional shm_open() call.  This
2172  * allows other consumers, like memfd_create(), to opt-in for CLOEXEC.  This
2173  * interface also includes a 'name' argument that is currently unused, but could
2174  * potentially be exported later via some interface for debugging purposes.
2175  * From the kernel's perspective, it is optional.  Individual consumers like
2176  * memfd_create() may require it in order to be compatible with other systems
2177  * implementing the same function.
2178  */
2179 int
2180 sys_shm_open2(struct thread *td, struct shm_open2_args *uap)
2181 {
2182
2183         return (kern_shm_open2(td, uap->path, uap->flags, uap->mode,
2184             uap->shmflags, NULL, uap->name));
2185 }