uipc_shm.c revision 254601
1175164Sjhb/*- 2225344Srwatson * Copyright (c) 2006, 2011 Robert N. M. Watson 3175164Sjhb * All rights reserved. 4175164Sjhb * 5175164Sjhb * Redistribution and use in source and binary forms, with or without 6175164Sjhb * modification, are permitted provided that the following conditions 7175164Sjhb * are met: 8175164Sjhb * 1. Redistributions of source code must retain the above copyright 9175164Sjhb * notice, this list of conditions and the following disclaimer. 10175164Sjhb * 2. Redistributions in binary form must reproduce the above copyright 11175164Sjhb * notice, this list of conditions and the following disclaimer in the 12175164Sjhb * documentation and/or other materials provided with the distribution. 13175164Sjhb * 14175164Sjhb * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15175164Sjhb * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16175164Sjhb * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17175164Sjhb * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18175164Sjhb * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19175164Sjhb * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20175164Sjhb * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21175164Sjhb * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22175164Sjhb * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23175164Sjhb * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24175164Sjhb * SUCH DAMAGE. 25175164Sjhb */ 26175164Sjhb 27175164Sjhb/* 28175164Sjhb * Support for shared swap-backed anonymous memory objects via 29175164Sjhb * shm_open(2) and shm_unlink(2). While most of the implementation is 30175164Sjhb * here, vm_mmap.c contains mapping logic changes. 31175164Sjhb * 32175164Sjhb * TODO: 33175164Sjhb * 34225344Srwatson * (1) Need to export data to a userland tool via a sysctl. Should ipcs(1) 35175164Sjhb * and ipcrm(1) be expanded or should new tools to manage both POSIX 36175164Sjhb * kernel semaphores and POSIX shared memory be written? 37175164Sjhb * 38225344Srwatson * (2) Add support for this file type to fstat(1). 39175164Sjhb * 40225344Srwatson * (3) Resource limits? Does this need its own resource limits or are the 41175164Sjhb * existing limits in mmap(2) sufficient? 42175164Sjhb */ 43175164Sjhb 44175164Sjhb#include <sys/cdefs.h> 45175164Sjhb__FBSDID("$FreeBSD: head/sys/kern/uipc_shm.c 254601 2013-08-21 17:23:24Z kib $"); 46175164Sjhb 47223692Sjonathan#include "opt_capsicum.h" 48223692Sjonathan 49175164Sjhb#include <sys/param.h> 50223692Sjonathan#include <sys/capability.h> 51175164Sjhb#include <sys/fcntl.h> 52175164Sjhb#include <sys/file.h> 53175164Sjhb#include <sys/filedesc.h> 54175164Sjhb#include <sys/fnv_hash.h> 55175164Sjhb#include <sys/kernel.h> 56175164Sjhb#include <sys/lock.h> 57175164Sjhb#include <sys/malloc.h> 58175164Sjhb#include <sys/mman.h> 59175164Sjhb#include <sys/mutex.h> 60224914Skib#include <sys/priv.h> 61175164Sjhb#include <sys/proc.h> 62175164Sjhb#include <sys/refcount.h> 63175164Sjhb#include <sys/resourcevar.h> 64248084Sattilio#include <sys/rwlock.h> 65175164Sjhb#include <sys/stat.h> 66175164Sjhb#include <sys/sysctl.h> 67175164Sjhb#include <sys/sysproto.h> 68175164Sjhb#include <sys/systm.h> 69175164Sjhb#include <sys/sx.h> 70175164Sjhb#include <sys/time.h> 71175164Sjhb#include <sys/vnode.h> 72175164Sjhb 73175164Sjhb#include <security/mac/mac_framework.h> 74175164Sjhb 75175164Sjhb#include <vm/vm.h> 76175164Sjhb#include <vm/vm_param.h> 77175164Sjhb#include <vm/pmap.h> 78228533Sjhb#include <vm/vm_extern.h> 79175164Sjhb#include <vm/vm_map.h> 80228509Sjhb#include <vm/vm_kern.h> 81175164Sjhb#include <vm/vm_object.h> 82175164Sjhb#include <vm/vm_page.h> 83229821Salc#include <vm/vm_pageout.h> 84175164Sjhb#include <vm/vm_pager.h> 85175164Sjhb#include <vm/swap_pager.h> 86175164Sjhb 87175164Sjhbstruct shm_mapping { 88175164Sjhb char *sm_path; 89175164Sjhb Fnv32_t sm_fnv; 90175164Sjhb struct shmfd *sm_shmfd; 91175164Sjhb LIST_ENTRY(shm_mapping) sm_link; 92175164Sjhb}; 93175164Sjhb 94175164Sjhbstatic MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); 95175164Sjhbstatic LIST_HEAD(, shm_mapping) *shm_dictionary; 96175164Sjhbstatic struct sx shm_dict_lock; 97175164Sjhbstatic struct mtx shm_timestamp_lock; 98175164Sjhbstatic u_long shm_hash; 99175164Sjhb 100175164Sjhb#define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) 101175164Sjhb 102175164Sjhbstatic int shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags); 103175164Sjhbstatic struct shmfd *shm_alloc(struct ucred *ucred, mode_t mode); 104175164Sjhbstatic void shm_dict_init(void *arg); 105175164Sjhbstatic void shm_drop(struct shmfd *shmfd); 106175164Sjhbstatic struct shmfd *shm_hold(struct shmfd *shmfd); 107175164Sjhbstatic void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); 108175164Sjhbstatic struct shmfd *shm_lookup(char *path, Fnv32_t fnv); 109175164Sjhbstatic int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 110194766Skibstatic int shm_dotruncate(struct shmfd *shmfd, off_t length); 111175164Sjhb 112175164Sjhbstatic fo_rdwr_t shm_read; 113175164Sjhbstatic fo_rdwr_t shm_write; 114175164Sjhbstatic fo_truncate_t shm_truncate; 115175164Sjhbstatic fo_ioctl_t shm_ioctl; 116175164Sjhbstatic fo_poll_t shm_poll; 117175164Sjhbstatic fo_kqfilter_t shm_kqfilter; 118175164Sjhbstatic fo_stat_t shm_stat; 119175164Sjhbstatic fo_close_t shm_close; 120224914Skibstatic fo_chmod_t shm_chmod; 121224914Skibstatic fo_chown_t shm_chown; 122175164Sjhb 123175164Sjhb/* File descriptor operations. */ 124175164Sjhbstatic struct fileops shm_ops = { 125175164Sjhb .fo_read = shm_read, 126175164Sjhb .fo_write = shm_write, 127175164Sjhb .fo_truncate = shm_truncate, 128175164Sjhb .fo_ioctl = shm_ioctl, 129175164Sjhb .fo_poll = shm_poll, 130175164Sjhb .fo_kqfilter = shm_kqfilter, 131175164Sjhb .fo_stat = shm_stat, 132175164Sjhb .fo_close = shm_close, 133224914Skib .fo_chmod = shm_chmod, 134224914Skib .fo_chown = shm_chown, 135254356Sglebius .fo_sendfile = invfo_sendfile, 136175164Sjhb .fo_flags = DFLAG_PASSABLE 137175164Sjhb}; 138175164Sjhb 139175164SjhbFEATURE(posix_shm, "POSIX shared memory"); 140175164Sjhb 141175164Sjhbstatic int 142254601Skibuiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 143254601Skib{ 144254601Skib vm_page_t m; 145254601Skib vm_pindex_t idx; 146254601Skib size_t tlen; 147254601Skib int error, offset, rv; 148254601Skib 149254601Skib idx = OFF_TO_IDX(uio->uio_offset); 150254601Skib offset = uio->uio_offset & PAGE_MASK; 151254601Skib tlen = MIN(PAGE_SIZE - offset, len); 152254601Skib 153254601Skib VM_OBJECT_WLOCK(obj); 154254601Skib 155254601Skib /* 156254601Skib * Parallel reads of the page content from disk are prevented 157254601Skib * by exclusive busy. 158254601Skib * 159254601Skib * Although the tmpfs vnode lock is held here, it is 160254601Skib * nonetheless safe to sleep waiting for a free page. The 161254601Skib * pageout daemon does not need to acquire the tmpfs vnode 162254601Skib * lock to page out tobj's pages because tobj is a OBJT_SWAP 163254601Skib * type object. 164254601Skib */ 165254601Skib m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 166254601Skib if (m->valid != VM_PAGE_BITS_ALL) { 167254601Skib if (vm_pager_has_page(obj, idx, NULL, NULL)) { 168254601Skib rv = vm_pager_get_pages(obj, &m, 1, 0); 169254601Skib m = vm_page_lookup(obj, idx); 170254601Skib if (m == NULL) { 171254601Skib printf( 172254601Skib "uiomove_object: vm_obj %p idx %jd null lookup rv %d\n", 173254601Skib obj, idx, rv); 174254601Skib VM_OBJECT_WUNLOCK(obj); 175254601Skib return (EIO); 176254601Skib } 177254601Skib if (rv != VM_PAGER_OK) { 178254601Skib printf( 179254601Skib "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n", 180254601Skib obj, idx, m->valid, rv); 181254601Skib vm_page_lock(m); 182254601Skib vm_page_free(m); 183254601Skib vm_page_unlock(m); 184254601Skib VM_OBJECT_WUNLOCK(obj); 185254601Skib return (EIO); 186254601Skib } 187254601Skib } else 188254601Skib vm_page_zero_invalid(m, TRUE); 189254601Skib } 190254601Skib vm_page_xunbusy(m); 191254601Skib vm_page_lock(m); 192254601Skib vm_page_hold(m); 193254601Skib vm_page_unlock(m); 194254601Skib VM_OBJECT_WUNLOCK(obj); 195254601Skib error = uiomove_fromphys(&m, offset, tlen, uio); 196254601Skib if (uio->uio_rw == UIO_WRITE && error == 0) { 197254601Skib VM_OBJECT_WLOCK(obj); 198254601Skib vm_page_dirty(m); 199254601Skib VM_OBJECT_WUNLOCK(obj); 200254601Skib } 201254601Skib vm_page_lock(m); 202254601Skib vm_page_unhold(m); 203254601Skib if (m->queue == PQ_NONE) { 204254601Skib vm_page_deactivate(m); 205254601Skib } else { 206254601Skib /* Requeue to maintain LRU ordering. */ 207254601Skib vm_page_requeue(m); 208254601Skib } 209254601Skib vm_page_unlock(m); 210254601Skib 211254601Skib return (error); 212254601Skib} 213254601Skib 214254601Skibint 215254601Skibuiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 216254601Skib{ 217254601Skib ssize_t resid; 218254601Skib size_t len; 219254601Skib int error; 220254601Skib 221254601Skib error = 0; 222254601Skib while ((resid = uio->uio_resid) > 0) { 223254601Skib if (obj_size <= uio->uio_offset) 224254601Skib break; 225254601Skib len = MIN(obj_size - uio->uio_offset, resid); 226254601Skib if (len == 0) 227254601Skib break; 228254601Skib error = uiomove_object_page(obj, len, uio); 229254601Skib if (error != 0 || resid == uio->uio_resid) 230254601Skib break; 231254601Skib } 232254601Skib return (error); 233254601Skib} 234254601Skib 235254601Skibstatic int 236175164Sjhbshm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 237175164Sjhb int flags, struct thread *td) 238175164Sjhb{ 239175164Sjhb 240175164Sjhb return (EOPNOTSUPP); 241175164Sjhb} 242175164Sjhb 243175164Sjhbstatic int 244175164Sjhbshm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 245175164Sjhb int flags, struct thread *td) 246175164Sjhb{ 247175164Sjhb 248175164Sjhb return (EOPNOTSUPP); 249175164Sjhb} 250175164Sjhb 251175164Sjhbstatic int 252175164Sjhbshm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 253175164Sjhb struct thread *td) 254175164Sjhb{ 255175164Sjhb struct shmfd *shmfd; 256175164Sjhb#ifdef MAC 257175164Sjhb int error; 258175164Sjhb#endif 259175164Sjhb 260175164Sjhb shmfd = fp->f_data; 261175164Sjhb#ifdef MAC 262175164Sjhb error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 263175164Sjhb if (error) 264175164Sjhb return (error); 265175164Sjhb#endif 266194766Skib return (shm_dotruncate(shmfd, length)); 267175164Sjhb} 268175164Sjhb 269175164Sjhbstatic int 270175164Sjhbshm_ioctl(struct file *fp, u_long com, void *data, 271175164Sjhb struct ucred *active_cred, struct thread *td) 272175164Sjhb{ 273175164Sjhb 274175164Sjhb return (EOPNOTSUPP); 275175164Sjhb} 276175164Sjhb 277175164Sjhbstatic int 278175164Sjhbshm_poll(struct file *fp, int events, struct ucred *active_cred, 279175164Sjhb struct thread *td) 280175164Sjhb{ 281175164Sjhb 282175164Sjhb return (EOPNOTSUPP); 283175164Sjhb} 284175164Sjhb 285175164Sjhbstatic int 286175164Sjhbshm_kqfilter(struct file *fp, struct knote *kn) 287175164Sjhb{ 288175164Sjhb 289175164Sjhb return (EOPNOTSUPP); 290175164Sjhb} 291175164Sjhb 292175164Sjhbstatic int 293175164Sjhbshm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 294175164Sjhb struct thread *td) 295175164Sjhb{ 296175164Sjhb struct shmfd *shmfd; 297175164Sjhb#ifdef MAC 298175164Sjhb int error; 299175164Sjhb#endif 300175164Sjhb 301175164Sjhb shmfd = fp->f_data; 302175164Sjhb 303175164Sjhb#ifdef MAC 304175164Sjhb error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 305175164Sjhb if (error) 306175164Sjhb return (error); 307175164Sjhb#endif 308175164Sjhb 309175164Sjhb /* 310175164Sjhb * Attempt to return sanish values for fstat() on a memory file 311175164Sjhb * descriptor. 312175164Sjhb */ 313175164Sjhb bzero(sb, sizeof(*sb)); 314175164Sjhb sb->st_blksize = PAGE_SIZE; 315175164Sjhb sb->st_size = shmfd->shm_size; 316175164Sjhb sb->st_blocks = (sb->st_size + sb->st_blksize - 1) / sb->st_blksize; 317224914Skib mtx_lock(&shm_timestamp_lock); 318205792Sed sb->st_atim = shmfd->shm_atime; 319205792Sed sb->st_ctim = shmfd->shm_ctime; 320205792Sed sb->st_mtim = shmfd->shm_mtime; 321224914Skib sb->st_birthtim = shmfd->shm_birthtime; 322224914Skib sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 323175164Sjhb sb->st_uid = shmfd->shm_uid; 324175164Sjhb sb->st_gid = shmfd->shm_gid; 325224914Skib mtx_unlock(&shm_timestamp_lock); 326175164Sjhb 327175164Sjhb return (0); 328175164Sjhb} 329175164Sjhb 330175164Sjhbstatic int 331175164Sjhbshm_close(struct file *fp, struct thread *td) 332175164Sjhb{ 333175164Sjhb struct shmfd *shmfd; 334175164Sjhb 335175164Sjhb shmfd = fp->f_data; 336175164Sjhb fp->f_data = NULL; 337175164Sjhb shm_drop(shmfd); 338175164Sjhb 339175164Sjhb return (0); 340175164Sjhb} 341175164Sjhb 342194766Skibstatic int 343175164Sjhbshm_dotruncate(struct shmfd *shmfd, off_t length) 344175164Sjhb{ 345175164Sjhb vm_object_t object; 346229821Salc vm_page_t m, ma[1]; 347229821Salc vm_pindex_t idx, nobjsize; 348194766Skib vm_ooffset_t delta; 349229821Salc int base, rv; 350175164Sjhb 351175164Sjhb object = shmfd->shm_object; 352248084Sattilio VM_OBJECT_WLOCK(object); 353175164Sjhb if (length == shmfd->shm_size) { 354248084Sattilio VM_OBJECT_WUNLOCK(object); 355194766Skib return (0); 356175164Sjhb } 357175164Sjhb nobjsize = OFF_TO_IDX(length + PAGE_MASK); 358175164Sjhb 359175164Sjhb /* Are we shrinking? If so, trim the end. */ 360175164Sjhb if (length < shmfd->shm_size) { 361228509Sjhb /* 362228509Sjhb * Disallow any requests to shrink the size if this 363228509Sjhb * object is mapped into the kernel. 364228509Sjhb */ 365228509Sjhb if (shmfd->shm_kmappings > 0) { 366248084Sattilio VM_OBJECT_WUNLOCK(object); 367228509Sjhb return (EBUSY); 368228509Sjhb } 369229821Salc 370229821Salc /* 371229821Salc * Zero the truncated part of the last page. 372229821Salc */ 373229821Salc base = length & PAGE_MASK; 374229821Salc if (base != 0) { 375229821Salc idx = OFF_TO_IDX(length); 376229821Salcretry: 377229821Salc m = vm_page_lookup(object, idx); 378229821Salc if (m != NULL) { 379254138Sattilio if (vm_page_sleep_if_busy(m, "shmtrc")) 380229821Salc goto retry; 381229821Salc } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 382229821Salc m = vm_page_alloc(object, idx, VM_ALLOC_NORMAL); 383229821Salc if (m == NULL) { 384248084Sattilio VM_OBJECT_WUNLOCK(object); 385229821Salc VM_WAIT; 386248084Sattilio VM_OBJECT_WLOCK(object); 387229821Salc goto retry; 388229821Salc } else if (m->valid != VM_PAGE_BITS_ALL) { 389229821Salc ma[0] = m; 390229821Salc rv = vm_pager_get_pages(object, ma, 1, 391229821Salc 0); 392229821Salc m = vm_page_lookup(object, idx); 393229821Salc } else 394229821Salc /* A cached page was reactivated. */ 395229821Salc rv = VM_PAGER_OK; 396229821Salc vm_page_lock(m); 397229821Salc if (rv == VM_PAGER_OK) { 398229821Salc vm_page_deactivate(m); 399229821Salc vm_page_unlock(m); 400254138Sattilio vm_page_xunbusy(m); 401229821Salc } else { 402229821Salc vm_page_free(m); 403229821Salc vm_page_unlock(m); 404248084Sattilio VM_OBJECT_WUNLOCK(object); 405229821Salc return (EIO); 406229821Salc } 407229821Salc } 408229821Salc if (m != NULL) { 409229821Salc pmap_zero_page_area(m, base, PAGE_SIZE - base); 410229821Salc KASSERT(m->valid == VM_PAGE_BITS_ALL, 411229821Salc ("shm_dotruncate: page %p is invalid", m)); 412229821Salc vm_page_dirty(m); 413229821Salc vm_pager_page_unswapped(m); 414229821Salc } 415229821Salc } 416194766Skib delta = ptoa(object->size - nobjsize); 417194766Skib 418175164Sjhb /* Toss in memory pages. */ 419175164Sjhb if (nobjsize < object->size) 420175164Sjhb vm_object_page_remove(object, nobjsize, object->size, 421223677Salc 0); 422175164Sjhb 423175164Sjhb /* Toss pages from swap. */ 424175164Sjhb if (object->type == OBJT_SWAP) 425194766Skib swap_pager_freespace(object, nobjsize, delta); 426175164Sjhb 427194766Skib /* Free the swap accounted for shm */ 428216128Strasz swap_release_by_cred(delta, object->cred); 429194766Skib object->charge -= delta; 430194766Skib } else { 431194766Skib /* Attempt to reserve the swap */ 432194766Skib delta = ptoa(nobjsize - object->size); 433216128Strasz if (!swap_reserve_by_cred(delta, object->cred)) { 434248084Sattilio VM_OBJECT_WUNLOCK(object); 435194766Skib return (ENOMEM); 436194766Skib } 437194766Skib object->charge += delta; 438175164Sjhb } 439175164Sjhb shmfd->shm_size = length; 440175164Sjhb mtx_lock(&shm_timestamp_lock); 441175164Sjhb vfs_timestamp(&shmfd->shm_ctime); 442175164Sjhb shmfd->shm_mtime = shmfd->shm_ctime; 443175164Sjhb mtx_unlock(&shm_timestamp_lock); 444175164Sjhb object->size = nobjsize; 445248084Sattilio VM_OBJECT_WUNLOCK(object); 446194766Skib return (0); 447175164Sjhb} 448175164Sjhb 449175164Sjhb/* 450175164Sjhb * shmfd object management including creation and reference counting 451175164Sjhb * routines. 452175164Sjhb */ 453175164Sjhbstatic struct shmfd * 454175164Sjhbshm_alloc(struct ucred *ucred, mode_t mode) 455175164Sjhb{ 456175164Sjhb struct shmfd *shmfd; 457175164Sjhb 458175164Sjhb shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 459175164Sjhb shmfd->shm_size = 0; 460175164Sjhb shmfd->shm_uid = ucred->cr_uid; 461175164Sjhb shmfd->shm_gid = ucred->cr_gid; 462175164Sjhb shmfd->shm_mode = mode; 463175164Sjhb shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL, 464194766Skib shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 465175164Sjhb KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 466248084Sattilio VM_OBJECT_WLOCK(shmfd->shm_object); 467178181Salc vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING); 468178181Salc vm_object_set_flag(shmfd->shm_object, OBJ_NOSPLIT); 469248084Sattilio VM_OBJECT_WUNLOCK(shmfd->shm_object); 470175164Sjhb vfs_timestamp(&shmfd->shm_birthtime); 471175164Sjhb shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 472175164Sjhb shmfd->shm_birthtime; 473175164Sjhb refcount_init(&shmfd->shm_refs, 1); 474175164Sjhb#ifdef MAC 475175164Sjhb mac_posixshm_init(shmfd); 476175164Sjhb mac_posixshm_create(ucred, shmfd); 477175164Sjhb#endif 478175164Sjhb 479175164Sjhb return (shmfd); 480175164Sjhb} 481175164Sjhb 482175164Sjhbstatic struct shmfd * 483175164Sjhbshm_hold(struct shmfd *shmfd) 484175164Sjhb{ 485175164Sjhb 486175164Sjhb refcount_acquire(&shmfd->shm_refs); 487175164Sjhb return (shmfd); 488175164Sjhb} 489175164Sjhb 490175164Sjhbstatic void 491175164Sjhbshm_drop(struct shmfd *shmfd) 492175164Sjhb{ 493175164Sjhb 494175164Sjhb if (refcount_release(&shmfd->shm_refs)) { 495175164Sjhb#ifdef MAC 496175164Sjhb mac_posixshm_destroy(shmfd); 497175164Sjhb#endif 498175164Sjhb vm_object_deallocate(shmfd->shm_object); 499175164Sjhb free(shmfd, M_SHMFD); 500175164Sjhb } 501175164Sjhb} 502175164Sjhb 503175164Sjhb/* 504175164Sjhb * Determine if the credentials have sufficient permissions for a 505175164Sjhb * specified combination of FREAD and FWRITE. 506175164Sjhb */ 507175164Sjhbstatic int 508175164Sjhbshm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 509175164Sjhb{ 510184413Strasz accmode_t accmode; 511224914Skib int error; 512175164Sjhb 513184413Strasz accmode = 0; 514175164Sjhb if (flags & FREAD) 515184413Strasz accmode |= VREAD; 516175164Sjhb if (flags & FWRITE) 517184413Strasz accmode |= VWRITE; 518224914Skib mtx_lock(&shm_timestamp_lock); 519224914Skib error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 520224914Skib accmode, ucred, NULL); 521224914Skib mtx_unlock(&shm_timestamp_lock); 522224914Skib return (error); 523175164Sjhb} 524175164Sjhb 525175164Sjhb/* 526175164Sjhb * Dictionary management. We maintain an in-kernel dictionary to map 527175164Sjhb * paths to shmfd objects. We use the FNV hash on the path to store 528175164Sjhb * the mappings in a hash table. 529175164Sjhb */ 530175164Sjhbstatic void 531175164Sjhbshm_dict_init(void *arg) 532175164Sjhb{ 533175164Sjhb 534175164Sjhb mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 535175164Sjhb sx_init(&shm_dict_lock, "shm dictionary"); 536175164Sjhb shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 537175164Sjhb} 538175164SjhbSYSINIT(shm_dict_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_dict_init, NULL); 539175164Sjhb 540175164Sjhbstatic struct shmfd * 541175164Sjhbshm_lookup(char *path, Fnv32_t fnv) 542175164Sjhb{ 543175164Sjhb struct shm_mapping *map; 544175164Sjhb 545175164Sjhb LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 546175164Sjhb if (map->sm_fnv != fnv) 547175164Sjhb continue; 548175164Sjhb if (strcmp(map->sm_path, path) == 0) 549175164Sjhb return (map->sm_shmfd); 550175164Sjhb } 551175164Sjhb 552175164Sjhb return (NULL); 553175164Sjhb} 554175164Sjhb 555175164Sjhbstatic void 556175164Sjhbshm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 557175164Sjhb{ 558175164Sjhb struct shm_mapping *map; 559175164Sjhb 560175164Sjhb map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 561175164Sjhb map->sm_path = path; 562175164Sjhb map->sm_fnv = fnv; 563175164Sjhb map->sm_shmfd = shm_hold(shmfd); 564233760Sjhb shmfd->shm_path = path; 565175164Sjhb LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 566175164Sjhb} 567175164Sjhb 568175164Sjhbstatic int 569175164Sjhbshm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 570175164Sjhb{ 571175164Sjhb struct shm_mapping *map; 572175164Sjhb int error; 573175164Sjhb 574175164Sjhb LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 575175164Sjhb if (map->sm_fnv != fnv) 576175164Sjhb continue; 577175164Sjhb if (strcmp(map->sm_path, path) == 0) { 578175164Sjhb#ifdef MAC 579175164Sjhb error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 580175164Sjhb if (error) 581175164Sjhb return (error); 582175164Sjhb#endif 583175164Sjhb error = shm_access(map->sm_shmfd, ucred, 584175164Sjhb FREAD | FWRITE); 585175164Sjhb if (error) 586175164Sjhb return (error); 587233760Sjhb map->sm_shmfd->shm_path = NULL; 588175164Sjhb LIST_REMOVE(map, sm_link); 589175164Sjhb shm_drop(map->sm_shmfd); 590175164Sjhb free(map->sm_path, M_SHMFD); 591175164Sjhb free(map, M_SHMFD); 592175164Sjhb return (0); 593175164Sjhb } 594175164Sjhb } 595175164Sjhb 596175164Sjhb return (ENOENT); 597175164Sjhb} 598175164Sjhb 599175164Sjhb/* System calls. */ 600175164Sjhbint 601225617Skmacysys_shm_open(struct thread *td, struct shm_open_args *uap) 602175164Sjhb{ 603175164Sjhb struct filedesc *fdp; 604175164Sjhb struct shmfd *shmfd; 605175164Sjhb struct file *fp; 606175164Sjhb char *path; 607175164Sjhb Fnv32_t fnv; 608175164Sjhb mode_t cmode; 609175164Sjhb int fd, error; 610175164Sjhb 611223692Sjonathan#ifdef CAPABILITY_MODE 612223692Sjonathan /* 613223692Sjonathan * shm_open(2) is only allowed for anonymous objects. 614223692Sjonathan */ 615223692Sjonathan if (IN_CAPABILITY_MODE(td) && (uap->path != SHM_ANON)) 616223692Sjonathan return (ECAPMODE); 617223692Sjonathan#endif 618223692Sjonathan 619175164Sjhb if ((uap->flags & O_ACCMODE) != O_RDONLY && 620175164Sjhb (uap->flags & O_ACCMODE) != O_RDWR) 621175164Sjhb return (EINVAL); 622175164Sjhb 623175164Sjhb if ((uap->flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC)) != 0) 624175164Sjhb return (EINVAL); 625175164Sjhb 626175164Sjhb fdp = td->td_proc->p_fd; 627175164Sjhb cmode = (uap->mode & ~fdp->fd_cmask) & ACCESSPERMS; 628175164Sjhb 629249233Sjilles error = falloc(td, &fp, &fd, O_CLOEXEC); 630175164Sjhb if (error) 631175164Sjhb return (error); 632175164Sjhb 633175164Sjhb /* A SHM_ANON path pointer creates an anonymous object. */ 634175164Sjhb if (uap->path == SHM_ANON) { 635175164Sjhb /* A read-only anonymous object is pointless. */ 636175164Sjhb if ((uap->flags & O_ACCMODE) == O_RDONLY) { 637175164Sjhb fdclose(fdp, fp, fd, td); 638175164Sjhb fdrop(fp, td); 639175164Sjhb return (EINVAL); 640175164Sjhb } 641175164Sjhb shmfd = shm_alloc(td->td_ucred, cmode); 642175164Sjhb } else { 643175164Sjhb path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 644175164Sjhb error = copyinstr(uap->path, path, MAXPATHLEN, NULL); 645175164Sjhb 646175164Sjhb /* Require paths to start with a '/' character. */ 647175164Sjhb if (error == 0 && path[0] != '/') 648175164Sjhb error = EINVAL; 649175164Sjhb if (error) { 650175164Sjhb fdclose(fdp, fp, fd, td); 651175164Sjhb fdrop(fp, td); 652175164Sjhb free(path, M_SHMFD); 653175164Sjhb return (error); 654175164Sjhb } 655175164Sjhb 656175164Sjhb fnv = fnv_32_str(path, FNV1_32_INIT); 657175164Sjhb sx_xlock(&shm_dict_lock); 658175164Sjhb shmfd = shm_lookup(path, fnv); 659175164Sjhb if (shmfd == NULL) { 660175164Sjhb /* Object does not yet exist, create it if requested. */ 661175164Sjhb if (uap->flags & O_CREAT) { 662225344Srwatson#ifdef MAC 663225344Srwatson error = mac_posixshm_check_create(td->td_ucred, 664225344Srwatson path); 665225344Srwatson if (error == 0) { 666225344Srwatson#endif 667225344Srwatson shmfd = shm_alloc(td->td_ucred, cmode); 668225344Srwatson shm_insert(path, fnv, shmfd); 669225344Srwatson#ifdef MAC 670225344Srwatson } 671225344Srwatson#endif 672175164Sjhb } else { 673175164Sjhb free(path, M_SHMFD); 674175164Sjhb error = ENOENT; 675175164Sjhb } 676175164Sjhb } else { 677175164Sjhb /* 678175164Sjhb * Object already exists, obtain a new 679175164Sjhb * reference if requested and permitted. 680175164Sjhb */ 681175164Sjhb free(path, M_SHMFD); 682175164Sjhb if ((uap->flags & (O_CREAT | O_EXCL)) == 683175164Sjhb (O_CREAT | O_EXCL)) 684175164Sjhb error = EEXIST; 685175164Sjhb else { 686175164Sjhb#ifdef MAC 687175164Sjhb error = mac_posixshm_check_open(td->td_ucred, 688225344Srwatson shmfd, FFLAGS(uap->flags & O_ACCMODE)); 689175164Sjhb if (error == 0) 690175164Sjhb#endif 691175164Sjhb error = shm_access(shmfd, td->td_ucred, 692175164Sjhb FFLAGS(uap->flags & O_ACCMODE)); 693175164Sjhb } 694175164Sjhb 695175164Sjhb /* 696175164Sjhb * Truncate the file back to zero length if 697175164Sjhb * O_TRUNC was specified and the object was 698175164Sjhb * opened with read/write. 699175164Sjhb */ 700175164Sjhb if (error == 0 && 701175164Sjhb (uap->flags & (O_ACCMODE | O_TRUNC)) == 702175164Sjhb (O_RDWR | O_TRUNC)) { 703175164Sjhb#ifdef MAC 704175164Sjhb error = mac_posixshm_check_truncate( 705175164Sjhb td->td_ucred, fp->f_cred, shmfd); 706175164Sjhb if (error == 0) 707175164Sjhb#endif 708175164Sjhb shm_dotruncate(shmfd, 0); 709175164Sjhb } 710175164Sjhb if (error == 0) 711175164Sjhb shm_hold(shmfd); 712175164Sjhb } 713175164Sjhb sx_xunlock(&shm_dict_lock); 714175164Sjhb 715175164Sjhb if (error) { 716175164Sjhb fdclose(fdp, fp, fd, td); 717175164Sjhb fdrop(fp, td); 718175164Sjhb return (error); 719175164Sjhb } 720175164Sjhb } 721175164Sjhb 722175164Sjhb finit(fp, FFLAGS(uap->flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 723175164Sjhb 724175164Sjhb td->td_retval[0] = fd; 725175164Sjhb fdrop(fp, td); 726175164Sjhb 727175164Sjhb return (0); 728175164Sjhb} 729175164Sjhb 730175164Sjhbint 731225617Skmacysys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 732175164Sjhb{ 733175164Sjhb char *path; 734175164Sjhb Fnv32_t fnv; 735175164Sjhb int error; 736175164Sjhb 737175164Sjhb path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 738175164Sjhb error = copyinstr(uap->path, path, MAXPATHLEN, NULL); 739175164Sjhb if (error) { 740175164Sjhb free(path, M_TEMP); 741175164Sjhb return (error); 742175164Sjhb } 743175164Sjhb 744175164Sjhb fnv = fnv_32_str(path, FNV1_32_INIT); 745175164Sjhb sx_xlock(&shm_dict_lock); 746175164Sjhb error = shm_remove(path, fnv, td->td_ucred); 747175164Sjhb sx_xunlock(&shm_dict_lock); 748175164Sjhb free(path, M_TEMP); 749175164Sjhb 750175164Sjhb return (error); 751175164Sjhb} 752175164Sjhb 753175164Sjhb/* 754175164Sjhb * mmap() helper to validate mmap() requests against shm object state 755175164Sjhb * and give mmap() the vm_object to use for the mapping. 756175164Sjhb */ 757175164Sjhbint 758175164Sjhbshm_mmap(struct shmfd *shmfd, vm_size_t objsize, vm_ooffset_t foff, 759175164Sjhb vm_object_t *obj) 760175164Sjhb{ 761175164Sjhb 762175164Sjhb /* 763175164Sjhb * XXXRW: This validation is probably insufficient, and subject to 764175164Sjhb * sign errors. It should be fixed. 765175164Sjhb */ 766185533Skan if (foff >= shmfd->shm_size || 767185533Skan foff + objsize > round_page(shmfd->shm_size)) 768175164Sjhb return (EINVAL); 769175164Sjhb 770175164Sjhb mtx_lock(&shm_timestamp_lock); 771175164Sjhb vfs_timestamp(&shmfd->shm_atime); 772175164Sjhb mtx_unlock(&shm_timestamp_lock); 773175164Sjhb vm_object_reference(shmfd->shm_object); 774175164Sjhb *obj = shmfd->shm_object; 775175164Sjhb return (0); 776175164Sjhb} 777224914Skib 778224914Skibstatic int 779224914Skibshm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 780224914Skib struct thread *td) 781224914Skib{ 782224914Skib struct shmfd *shmfd; 783224914Skib int error; 784224914Skib 785224914Skib error = 0; 786224914Skib shmfd = fp->f_data; 787224914Skib mtx_lock(&shm_timestamp_lock); 788224914Skib /* 789224914Skib * SUSv4 says that x bits of permission need not be affected. 790224914Skib * Be consistent with our shm_open there. 791224914Skib */ 792224914Skib#ifdef MAC 793224914Skib error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 794224914Skib if (error != 0) 795224914Skib goto out; 796224914Skib#endif 797224914Skib error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 798224914Skib shmfd->shm_gid, VADMIN, active_cred, NULL); 799224914Skib if (error != 0) 800224914Skib goto out; 801224914Skib shmfd->shm_mode = mode & ACCESSPERMS; 802224914Skibout: 803224914Skib mtx_unlock(&shm_timestamp_lock); 804224914Skib return (error); 805224914Skib} 806224914Skib 807224914Skibstatic int 808224914Skibshm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 809224914Skib struct thread *td) 810224914Skib{ 811224914Skib struct shmfd *shmfd; 812224914Skib int error; 813224914Skib 814224935Skib error = 0; 815224914Skib shmfd = fp->f_data; 816224914Skib mtx_lock(&shm_timestamp_lock); 817224914Skib#ifdef MAC 818224914Skib error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 819224914Skib if (error != 0) 820224914Skib goto out; 821224914Skib#endif 822224914Skib if (uid == (uid_t)-1) 823224914Skib uid = shmfd->shm_uid; 824224914Skib if (gid == (gid_t)-1) 825224914Skib gid = shmfd->shm_gid; 826224914Skib if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 827224914Skib (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 828224914Skib (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0))) 829224914Skib goto out; 830224914Skib shmfd->shm_uid = uid; 831224914Skib shmfd->shm_gid = gid; 832224914Skibout: 833224914Skib mtx_unlock(&shm_timestamp_lock); 834224914Skib return (error); 835224914Skib} 836228509Sjhb 837228509Sjhb/* 838228509Sjhb * Helper routines to allow the backing object of a shared memory file 839228509Sjhb * descriptor to be mapped in the kernel. 840228509Sjhb */ 841228509Sjhbint 842228509Sjhbshm_map(struct file *fp, size_t size, off_t offset, void **memp) 843228509Sjhb{ 844228509Sjhb struct shmfd *shmfd; 845228509Sjhb vm_offset_t kva, ofs; 846228509Sjhb vm_object_t obj; 847228509Sjhb int rv; 848228509Sjhb 849228509Sjhb if (fp->f_type != DTYPE_SHM) 850228509Sjhb return (EINVAL); 851228509Sjhb shmfd = fp->f_data; 852228509Sjhb obj = shmfd->shm_object; 853248084Sattilio VM_OBJECT_WLOCK(obj); 854228509Sjhb /* 855228509Sjhb * XXXRW: This validation is probably insufficient, and subject to 856228509Sjhb * sign errors. It should be fixed. 857228509Sjhb */ 858228509Sjhb if (offset >= shmfd->shm_size || 859228509Sjhb offset + size > round_page(shmfd->shm_size)) { 860248084Sattilio VM_OBJECT_WUNLOCK(obj); 861228509Sjhb return (EINVAL); 862228509Sjhb } 863228509Sjhb 864228509Sjhb shmfd->shm_kmappings++; 865228509Sjhb vm_object_reference_locked(obj); 866248084Sattilio VM_OBJECT_WUNLOCK(obj); 867228509Sjhb 868228509Sjhb /* Map the object into the kernel_map and wire it. */ 869228509Sjhb kva = vm_map_min(kernel_map); 870228509Sjhb ofs = offset & PAGE_MASK; 871228509Sjhb offset = trunc_page(offset); 872228509Sjhb size = round_page(size + ofs); 873228509Sjhb rv = vm_map_find(kernel_map, obj, offset, &kva, size, 874253620Sjhb VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 875228509Sjhb VM_PROT_READ | VM_PROT_WRITE, 0); 876228509Sjhb if (rv == KERN_SUCCESS) { 877228509Sjhb rv = vm_map_wire(kernel_map, kva, kva + size, 878228509Sjhb VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 879228509Sjhb if (rv == KERN_SUCCESS) { 880228509Sjhb *memp = (void *)(kva + ofs); 881228509Sjhb return (0); 882228509Sjhb } 883228509Sjhb vm_map_remove(kernel_map, kva, kva + size); 884228509Sjhb } else 885228509Sjhb vm_object_deallocate(obj); 886228509Sjhb 887228509Sjhb /* On failure, drop our mapping reference. */ 888248084Sattilio VM_OBJECT_WLOCK(obj); 889228509Sjhb shmfd->shm_kmappings--; 890248084Sattilio VM_OBJECT_WUNLOCK(obj); 891228509Sjhb 892228533Sjhb return (vm_mmap_to_errno(rv)); 893228509Sjhb} 894228509Sjhb 895228509Sjhb/* 896228509Sjhb * We require the caller to unmap the entire entry. This allows us to 897228509Sjhb * safely decrement shm_kmappings when a mapping is removed. 898228509Sjhb */ 899228509Sjhbint 900228509Sjhbshm_unmap(struct file *fp, void *mem, size_t size) 901228509Sjhb{ 902228509Sjhb struct shmfd *shmfd; 903228509Sjhb vm_map_entry_t entry; 904228509Sjhb vm_offset_t kva, ofs; 905228509Sjhb vm_object_t obj; 906228509Sjhb vm_pindex_t pindex; 907228509Sjhb vm_prot_t prot; 908228509Sjhb boolean_t wired; 909228509Sjhb vm_map_t map; 910228509Sjhb int rv; 911228509Sjhb 912228509Sjhb if (fp->f_type != DTYPE_SHM) 913228509Sjhb return (EINVAL); 914228509Sjhb shmfd = fp->f_data; 915228509Sjhb kva = (vm_offset_t)mem; 916228509Sjhb ofs = kva & PAGE_MASK; 917228509Sjhb kva = trunc_page(kva); 918228509Sjhb size = round_page(size + ofs); 919228509Sjhb map = kernel_map; 920228509Sjhb rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 921228509Sjhb &obj, &pindex, &prot, &wired); 922228509Sjhb if (rv != KERN_SUCCESS) 923228509Sjhb return (EINVAL); 924228509Sjhb if (entry->start != kva || entry->end != kva + size) { 925228509Sjhb vm_map_lookup_done(map, entry); 926228509Sjhb return (EINVAL); 927228509Sjhb } 928228509Sjhb vm_map_lookup_done(map, entry); 929228509Sjhb if (obj != shmfd->shm_object) 930228509Sjhb return (EINVAL); 931228509Sjhb vm_map_remove(map, kva, kva + size); 932248084Sattilio VM_OBJECT_WLOCK(obj); 933228509Sjhb KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 934228509Sjhb shmfd->shm_kmappings--; 935248084Sattilio VM_OBJECT_WUNLOCK(obj); 936228509Sjhb return (0); 937228509Sjhb} 938233760Sjhb 939233760Sjhbvoid 940233760Sjhbshm_path(struct shmfd *shmfd, char *path, size_t size) 941233760Sjhb{ 942233760Sjhb 943233760Sjhb if (shmfd->shm_path == NULL) 944233760Sjhb return; 945233760Sjhb sx_slock(&shm_dict_lock); 946233760Sjhb if (shmfd->shm_path != NULL) 947233760Sjhb strlcpy(path, shmfd->shm_path, size); 948233760Sjhb sx_sunlock(&shm_dict_lock); 949233760Sjhb} 950