uipc_shm.c revision 253620
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 253620 2013-07-24 20:34:25Z jhb $"); 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, 135175164Sjhb .fo_flags = DFLAG_PASSABLE 136175164Sjhb}; 137175164Sjhb 138175164SjhbFEATURE(posix_shm, "POSIX shared memory"); 139175164Sjhb 140175164Sjhbstatic int 141175164Sjhbshm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 142175164Sjhb int flags, struct thread *td) 143175164Sjhb{ 144175164Sjhb 145175164Sjhb return (EOPNOTSUPP); 146175164Sjhb} 147175164Sjhb 148175164Sjhbstatic int 149175164Sjhbshm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 150175164Sjhb int flags, struct thread *td) 151175164Sjhb{ 152175164Sjhb 153175164Sjhb return (EOPNOTSUPP); 154175164Sjhb} 155175164Sjhb 156175164Sjhbstatic int 157175164Sjhbshm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 158175164Sjhb struct thread *td) 159175164Sjhb{ 160175164Sjhb struct shmfd *shmfd; 161175164Sjhb#ifdef MAC 162175164Sjhb int error; 163175164Sjhb#endif 164175164Sjhb 165175164Sjhb shmfd = fp->f_data; 166175164Sjhb#ifdef MAC 167175164Sjhb error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 168175164Sjhb if (error) 169175164Sjhb return (error); 170175164Sjhb#endif 171194766Skib return (shm_dotruncate(shmfd, length)); 172175164Sjhb} 173175164Sjhb 174175164Sjhbstatic int 175175164Sjhbshm_ioctl(struct file *fp, u_long com, void *data, 176175164Sjhb struct ucred *active_cred, struct thread *td) 177175164Sjhb{ 178175164Sjhb 179175164Sjhb return (EOPNOTSUPP); 180175164Sjhb} 181175164Sjhb 182175164Sjhbstatic int 183175164Sjhbshm_poll(struct file *fp, int events, struct ucred *active_cred, 184175164Sjhb struct thread *td) 185175164Sjhb{ 186175164Sjhb 187175164Sjhb return (EOPNOTSUPP); 188175164Sjhb} 189175164Sjhb 190175164Sjhbstatic int 191175164Sjhbshm_kqfilter(struct file *fp, struct knote *kn) 192175164Sjhb{ 193175164Sjhb 194175164Sjhb return (EOPNOTSUPP); 195175164Sjhb} 196175164Sjhb 197175164Sjhbstatic int 198175164Sjhbshm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 199175164Sjhb struct thread *td) 200175164Sjhb{ 201175164Sjhb struct shmfd *shmfd; 202175164Sjhb#ifdef MAC 203175164Sjhb int error; 204175164Sjhb#endif 205175164Sjhb 206175164Sjhb shmfd = fp->f_data; 207175164Sjhb 208175164Sjhb#ifdef MAC 209175164Sjhb error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 210175164Sjhb if (error) 211175164Sjhb return (error); 212175164Sjhb#endif 213175164Sjhb 214175164Sjhb /* 215175164Sjhb * Attempt to return sanish values for fstat() on a memory file 216175164Sjhb * descriptor. 217175164Sjhb */ 218175164Sjhb bzero(sb, sizeof(*sb)); 219175164Sjhb sb->st_blksize = PAGE_SIZE; 220175164Sjhb sb->st_size = shmfd->shm_size; 221175164Sjhb sb->st_blocks = (sb->st_size + sb->st_blksize - 1) / sb->st_blksize; 222224914Skib mtx_lock(&shm_timestamp_lock); 223205792Sed sb->st_atim = shmfd->shm_atime; 224205792Sed sb->st_ctim = shmfd->shm_ctime; 225205792Sed sb->st_mtim = shmfd->shm_mtime; 226224914Skib sb->st_birthtim = shmfd->shm_birthtime; 227224914Skib sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 228175164Sjhb sb->st_uid = shmfd->shm_uid; 229175164Sjhb sb->st_gid = shmfd->shm_gid; 230224914Skib mtx_unlock(&shm_timestamp_lock); 231175164Sjhb 232175164Sjhb return (0); 233175164Sjhb} 234175164Sjhb 235175164Sjhbstatic int 236175164Sjhbshm_close(struct file *fp, struct thread *td) 237175164Sjhb{ 238175164Sjhb struct shmfd *shmfd; 239175164Sjhb 240175164Sjhb shmfd = fp->f_data; 241175164Sjhb fp->f_data = NULL; 242175164Sjhb shm_drop(shmfd); 243175164Sjhb 244175164Sjhb return (0); 245175164Sjhb} 246175164Sjhb 247194766Skibstatic int 248175164Sjhbshm_dotruncate(struct shmfd *shmfd, off_t length) 249175164Sjhb{ 250175164Sjhb vm_object_t object; 251229821Salc vm_page_t m, ma[1]; 252229821Salc vm_pindex_t idx, nobjsize; 253194766Skib vm_ooffset_t delta; 254229821Salc int base, rv; 255175164Sjhb 256175164Sjhb object = shmfd->shm_object; 257248084Sattilio VM_OBJECT_WLOCK(object); 258175164Sjhb if (length == shmfd->shm_size) { 259248084Sattilio VM_OBJECT_WUNLOCK(object); 260194766Skib return (0); 261175164Sjhb } 262175164Sjhb nobjsize = OFF_TO_IDX(length + PAGE_MASK); 263175164Sjhb 264175164Sjhb /* Are we shrinking? If so, trim the end. */ 265175164Sjhb if (length < shmfd->shm_size) { 266228509Sjhb /* 267228509Sjhb * Disallow any requests to shrink the size if this 268228509Sjhb * object is mapped into the kernel. 269228509Sjhb */ 270228509Sjhb if (shmfd->shm_kmappings > 0) { 271248084Sattilio VM_OBJECT_WUNLOCK(object); 272228509Sjhb return (EBUSY); 273228509Sjhb } 274229821Salc 275229821Salc /* 276229821Salc * Zero the truncated part of the last page. 277229821Salc */ 278229821Salc base = length & PAGE_MASK; 279229821Salc if (base != 0) { 280229821Salc idx = OFF_TO_IDX(length); 281229821Salcretry: 282229821Salc m = vm_page_lookup(object, idx); 283229821Salc if (m != NULL) { 284229821Salc if ((m->oflags & VPO_BUSY) != 0 || 285229821Salc m->busy != 0) { 286229821Salc vm_page_sleep(m, "shmtrc"); 287229821Salc goto retry; 288229821Salc } 289229821Salc } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 290229821Salc m = vm_page_alloc(object, idx, VM_ALLOC_NORMAL); 291229821Salc if (m == NULL) { 292248084Sattilio VM_OBJECT_WUNLOCK(object); 293229821Salc VM_WAIT; 294248084Sattilio VM_OBJECT_WLOCK(object); 295229821Salc goto retry; 296229821Salc } else if (m->valid != VM_PAGE_BITS_ALL) { 297229821Salc ma[0] = m; 298229821Salc rv = vm_pager_get_pages(object, ma, 1, 299229821Salc 0); 300229821Salc m = vm_page_lookup(object, idx); 301229821Salc } else 302229821Salc /* A cached page was reactivated. */ 303229821Salc rv = VM_PAGER_OK; 304229821Salc vm_page_lock(m); 305229821Salc if (rv == VM_PAGER_OK) { 306229821Salc vm_page_deactivate(m); 307229821Salc vm_page_unlock(m); 308229821Salc vm_page_wakeup(m); 309229821Salc } else { 310229821Salc vm_page_free(m); 311229821Salc vm_page_unlock(m); 312248084Sattilio VM_OBJECT_WUNLOCK(object); 313229821Salc return (EIO); 314229821Salc } 315229821Salc } 316229821Salc if (m != NULL) { 317229821Salc pmap_zero_page_area(m, base, PAGE_SIZE - base); 318229821Salc KASSERT(m->valid == VM_PAGE_BITS_ALL, 319229821Salc ("shm_dotruncate: page %p is invalid", m)); 320229821Salc vm_page_dirty(m); 321229821Salc vm_pager_page_unswapped(m); 322229821Salc } 323229821Salc } 324194766Skib delta = ptoa(object->size - nobjsize); 325194766Skib 326175164Sjhb /* Toss in memory pages. */ 327175164Sjhb if (nobjsize < object->size) 328175164Sjhb vm_object_page_remove(object, nobjsize, object->size, 329223677Salc 0); 330175164Sjhb 331175164Sjhb /* Toss pages from swap. */ 332175164Sjhb if (object->type == OBJT_SWAP) 333194766Skib swap_pager_freespace(object, nobjsize, delta); 334175164Sjhb 335194766Skib /* Free the swap accounted for shm */ 336216128Strasz swap_release_by_cred(delta, object->cred); 337194766Skib object->charge -= delta; 338194766Skib } else { 339194766Skib /* Attempt to reserve the swap */ 340194766Skib delta = ptoa(nobjsize - object->size); 341216128Strasz if (!swap_reserve_by_cred(delta, object->cred)) { 342248084Sattilio VM_OBJECT_WUNLOCK(object); 343194766Skib return (ENOMEM); 344194766Skib } 345194766Skib object->charge += delta; 346175164Sjhb } 347175164Sjhb shmfd->shm_size = length; 348175164Sjhb mtx_lock(&shm_timestamp_lock); 349175164Sjhb vfs_timestamp(&shmfd->shm_ctime); 350175164Sjhb shmfd->shm_mtime = shmfd->shm_ctime; 351175164Sjhb mtx_unlock(&shm_timestamp_lock); 352175164Sjhb object->size = nobjsize; 353248084Sattilio VM_OBJECT_WUNLOCK(object); 354194766Skib return (0); 355175164Sjhb} 356175164Sjhb 357175164Sjhb/* 358175164Sjhb * shmfd object management including creation and reference counting 359175164Sjhb * routines. 360175164Sjhb */ 361175164Sjhbstatic struct shmfd * 362175164Sjhbshm_alloc(struct ucred *ucred, mode_t mode) 363175164Sjhb{ 364175164Sjhb struct shmfd *shmfd; 365175164Sjhb 366175164Sjhb shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 367175164Sjhb shmfd->shm_size = 0; 368175164Sjhb shmfd->shm_uid = ucred->cr_uid; 369175164Sjhb shmfd->shm_gid = ucred->cr_gid; 370175164Sjhb shmfd->shm_mode = mode; 371175164Sjhb shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL, 372194766Skib shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 373175164Sjhb KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 374248084Sattilio VM_OBJECT_WLOCK(shmfd->shm_object); 375178181Salc vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING); 376178181Salc vm_object_set_flag(shmfd->shm_object, OBJ_NOSPLIT); 377248084Sattilio VM_OBJECT_WUNLOCK(shmfd->shm_object); 378175164Sjhb vfs_timestamp(&shmfd->shm_birthtime); 379175164Sjhb shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 380175164Sjhb shmfd->shm_birthtime; 381175164Sjhb refcount_init(&shmfd->shm_refs, 1); 382175164Sjhb#ifdef MAC 383175164Sjhb mac_posixshm_init(shmfd); 384175164Sjhb mac_posixshm_create(ucred, shmfd); 385175164Sjhb#endif 386175164Sjhb 387175164Sjhb return (shmfd); 388175164Sjhb} 389175164Sjhb 390175164Sjhbstatic struct shmfd * 391175164Sjhbshm_hold(struct shmfd *shmfd) 392175164Sjhb{ 393175164Sjhb 394175164Sjhb refcount_acquire(&shmfd->shm_refs); 395175164Sjhb return (shmfd); 396175164Sjhb} 397175164Sjhb 398175164Sjhbstatic void 399175164Sjhbshm_drop(struct shmfd *shmfd) 400175164Sjhb{ 401175164Sjhb 402175164Sjhb if (refcount_release(&shmfd->shm_refs)) { 403175164Sjhb#ifdef MAC 404175164Sjhb mac_posixshm_destroy(shmfd); 405175164Sjhb#endif 406175164Sjhb vm_object_deallocate(shmfd->shm_object); 407175164Sjhb free(shmfd, M_SHMFD); 408175164Sjhb } 409175164Sjhb} 410175164Sjhb 411175164Sjhb/* 412175164Sjhb * Determine if the credentials have sufficient permissions for a 413175164Sjhb * specified combination of FREAD and FWRITE. 414175164Sjhb */ 415175164Sjhbstatic int 416175164Sjhbshm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 417175164Sjhb{ 418184413Strasz accmode_t accmode; 419224914Skib int error; 420175164Sjhb 421184413Strasz accmode = 0; 422175164Sjhb if (flags & FREAD) 423184413Strasz accmode |= VREAD; 424175164Sjhb if (flags & FWRITE) 425184413Strasz accmode |= VWRITE; 426224914Skib mtx_lock(&shm_timestamp_lock); 427224914Skib error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 428224914Skib accmode, ucred, NULL); 429224914Skib mtx_unlock(&shm_timestamp_lock); 430224914Skib return (error); 431175164Sjhb} 432175164Sjhb 433175164Sjhb/* 434175164Sjhb * Dictionary management. We maintain an in-kernel dictionary to map 435175164Sjhb * paths to shmfd objects. We use the FNV hash on the path to store 436175164Sjhb * the mappings in a hash table. 437175164Sjhb */ 438175164Sjhbstatic void 439175164Sjhbshm_dict_init(void *arg) 440175164Sjhb{ 441175164Sjhb 442175164Sjhb mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 443175164Sjhb sx_init(&shm_dict_lock, "shm dictionary"); 444175164Sjhb shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 445175164Sjhb} 446175164SjhbSYSINIT(shm_dict_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_dict_init, NULL); 447175164Sjhb 448175164Sjhbstatic struct shmfd * 449175164Sjhbshm_lookup(char *path, Fnv32_t fnv) 450175164Sjhb{ 451175164Sjhb struct shm_mapping *map; 452175164Sjhb 453175164Sjhb LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 454175164Sjhb if (map->sm_fnv != fnv) 455175164Sjhb continue; 456175164Sjhb if (strcmp(map->sm_path, path) == 0) 457175164Sjhb return (map->sm_shmfd); 458175164Sjhb } 459175164Sjhb 460175164Sjhb return (NULL); 461175164Sjhb} 462175164Sjhb 463175164Sjhbstatic void 464175164Sjhbshm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 465175164Sjhb{ 466175164Sjhb struct shm_mapping *map; 467175164Sjhb 468175164Sjhb map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 469175164Sjhb map->sm_path = path; 470175164Sjhb map->sm_fnv = fnv; 471175164Sjhb map->sm_shmfd = shm_hold(shmfd); 472233760Sjhb shmfd->shm_path = path; 473175164Sjhb LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 474175164Sjhb} 475175164Sjhb 476175164Sjhbstatic int 477175164Sjhbshm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 478175164Sjhb{ 479175164Sjhb struct shm_mapping *map; 480175164Sjhb int error; 481175164Sjhb 482175164Sjhb LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 483175164Sjhb if (map->sm_fnv != fnv) 484175164Sjhb continue; 485175164Sjhb if (strcmp(map->sm_path, path) == 0) { 486175164Sjhb#ifdef MAC 487175164Sjhb error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 488175164Sjhb if (error) 489175164Sjhb return (error); 490175164Sjhb#endif 491175164Sjhb error = shm_access(map->sm_shmfd, ucred, 492175164Sjhb FREAD | FWRITE); 493175164Sjhb if (error) 494175164Sjhb return (error); 495233760Sjhb map->sm_shmfd->shm_path = NULL; 496175164Sjhb LIST_REMOVE(map, sm_link); 497175164Sjhb shm_drop(map->sm_shmfd); 498175164Sjhb free(map->sm_path, M_SHMFD); 499175164Sjhb free(map, M_SHMFD); 500175164Sjhb return (0); 501175164Sjhb } 502175164Sjhb } 503175164Sjhb 504175164Sjhb return (ENOENT); 505175164Sjhb} 506175164Sjhb 507175164Sjhb/* System calls. */ 508175164Sjhbint 509225617Skmacysys_shm_open(struct thread *td, struct shm_open_args *uap) 510175164Sjhb{ 511175164Sjhb struct filedesc *fdp; 512175164Sjhb struct shmfd *shmfd; 513175164Sjhb struct file *fp; 514175164Sjhb char *path; 515175164Sjhb Fnv32_t fnv; 516175164Sjhb mode_t cmode; 517175164Sjhb int fd, error; 518175164Sjhb 519223692Sjonathan#ifdef CAPABILITY_MODE 520223692Sjonathan /* 521223692Sjonathan * shm_open(2) is only allowed for anonymous objects. 522223692Sjonathan */ 523223692Sjonathan if (IN_CAPABILITY_MODE(td) && (uap->path != SHM_ANON)) 524223692Sjonathan return (ECAPMODE); 525223692Sjonathan#endif 526223692Sjonathan 527175164Sjhb if ((uap->flags & O_ACCMODE) != O_RDONLY && 528175164Sjhb (uap->flags & O_ACCMODE) != O_RDWR) 529175164Sjhb return (EINVAL); 530175164Sjhb 531175164Sjhb if ((uap->flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC)) != 0) 532175164Sjhb return (EINVAL); 533175164Sjhb 534175164Sjhb fdp = td->td_proc->p_fd; 535175164Sjhb cmode = (uap->mode & ~fdp->fd_cmask) & ACCESSPERMS; 536175164Sjhb 537249233Sjilles error = falloc(td, &fp, &fd, O_CLOEXEC); 538175164Sjhb if (error) 539175164Sjhb return (error); 540175164Sjhb 541175164Sjhb /* A SHM_ANON path pointer creates an anonymous object. */ 542175164Sjhb if (uap->path == SHM_ANON) { 543175164Sjhb /* A read-only anonymous object is pointless. */ 544175164Sjhb if ((uap->flags & O_ACCMODE) == O_RDONLY) { 545175164Sjhb fdclose(fdp, fp, fd, td); 546175164Sjhb fdrop(fp, td); 547175164Sjhb return (EINVAL); 548175164Sjhb } 549175164Sjhb shmfd = shm_alloc(td->td_ucred, cmode); 550175164Sjhb } else { 551175164Sjhb path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 552175164Sjhb error = copyinstr(uap->path, path, MAXPATHLEN, NULL); 553175164Sjhb 554175164Sjhb /* Require paths to start with a '/' character. */ 555175164Sjhb if (error == 0 && path[0] != '/') 556175164Sjhb error = EINVAL; 557175164Sjhb if (error) { 558175164Sjhb fdclose(fdp, fp, fd, td); 559175164Sjhb fdrop(fp, td); 560175164Sjhb free(path, M_SHMFD); 561175164Sjhb return (error); 562175164Sjhb } 563175164Sjhb 564175164Sjhb fnv = fnv_32_str(path, FNV1_32_INIT); 565175164Sjhb sx_xlock(&shm_dict_lock); 566175164Sjhb shmfd = shm_lookup(path, fnv); 567175164Sjhb if (shmfd == NULL) { 568175164Sjhb /* Object does not yet exist, create it if requested. */ 569175164Sjhb if (uap->flags & O_CREAT) { 570225344Srwatson#ifdef MAC 571225344Srwatson error = mac_posixshm_check_create(td->td_ucred, 572225344Srwatson path); 573225344Srwatson if (error == 0) { 574225344Srwatson#endif 575225344Srwatson shmfd = shm_alloc(td->td_ucred, cmode); 576225344Srwatson shm_insert(path, fnv, shmfd); 577225344Srwatson#ifdef MAC 578225344Srwatson } 579225344Srwatson#endif 580175164Sjhb } else { 581175164Sjhb free(path, M_SHMFD); 582175164Sjhb error = ENOENT; 583175164Sjhb } 584175164Sjhb } else { 585175164Sjhb /* 586175164Sjhb * Object already exists, obtain a new 587175164Sjhb * reference if requested and permitted. 588175164Sjhb */ 589175164Sjhb free(path, M_SHMFD); 590175164Sjhb if ((uap->flags & (O_CREAT | O_EXCL)) == 591175164Sjhb (O_CREAT | O_EXCL)) 592175164Sjhb error = EEXIST; 593175164Sjhb else { 594175164Sjhb#ifdef MAC 595175164Sjhb error = mac_posixshm_check_open(td->td_ucred, 596225344Srwatson shmfd, FFLAGS(uap->flags & O_ACCMODE)); 597175164Sjhb if (error == 0) 598175164Sjhb#endif 599175164Sjhb error = shm_access(shmfd, td->td_ucred, 600175164Sjhb FFLAGS(uap->flags & O_ACCMODE)); 601175164Sjhb } 602175164Sjhb 603175164Sjhb /* 604175164Sjhb * Truncate the file back to zero length if 605175164Sjhb * O_TRUNC was specified and the object was 606175164Sjhb * opened with read/write. 607175164Sjhb */ 608175164Sjhb if (error == 0 && 609175164Sjhb (uap->flags & (O_ACCMODE | O_TRUNC)) == 610175164Sjhb (O_RDWR | O_TRUNC)) { 611175164Sjhb#ifdef MAC 612175164Sjhb error = mac_posixshm_check_truncate( 613175164Sjhb td->td_ucred, fp->f_cred, shmfd); 614175164Sjhb if (error == 0) 615175164Sjhb#endif 616175164Sjhb shm_dotruncate(shmfd, 0); 617175164Sjhb } 618175164Sjhb if (error == 0) 619175164Sjhb shm_hold(shmfd); 620175164Sjhb } 621175164Sjhb sx_xunlock(&shm_dict_lock); 622175164Sjhb 623175164Sjhb if (error) { 624175164Sjhb fdclose(fdp, fp, fd, td); 625175164Sjhb fdrop(fp, td); 626175164Sjhb return (error); 627175164Sjhb } 628175164Sjhb } 629175164Sjhb 630175164Sjhb finit(fp, FFLAGS(uap->flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 631175164Sjhb 632175164Sjhb td->td_retval[0] = fd; 633175164Sjhb fdrop(fp, td); 634175164Sjhb 635175164Sjhb return (0); 636175164Sjhb} 637175164Sjhb 638175164Sjhbint 639225617Skmacysys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 640175164Sjhb{ 641175164Sjhb char *path; 642175164Sjhb Fnv32_t fnv; 643175164Sjhb int error; 644175164Sjhb 645175164Sjhb path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 646175164Sjhb error = copyinstr(uap->path, path, MAXPATHLEN, NULL); 647175164Sjhb if (error) { 648175164Sjhb free(path, M_TEMP); 649175164Sjhb return (error); 650175164Sjhb } 651175164Sjhb 652175164Sjhb fnv = fnv_32_str(path, FNV1_32_INIT); 653175164Sjhb sx_xlock(&shm_dict_lock); 654175164Sjhb error = shm_remove(path, fnv, td->td_ucred); 655175164Sjhb sx_xunlock(&shm_dict_lock); 656175164Sjhb free(path, M_TEMP); 657175164Sjhb 658175164Sjhb return (error); 659175164Sjhb} 660175164Sjhb 661175164Sjhb/* 662175164Sjhb * mmap() helper to validate mmap() requests against shm object state 663175164Sjhb * and give mmap() the vm_object to use for the mapping. 664175164Sjhb */ 665175164Sjhbint 666175164Sjhbshm_mmap(struct shmfd *shmfd, vm_size_t objsize, vm_ooffset_t foff, 667175164Sjhb vm_object_t *obj) 668175164Sjhb{ 669175164Sjhb 670175164Sjhb /* 671175164Sjhb * XXXRW: This validation is probably insufficient, and subject to 672175164Sjhb * sign errors. It should be fixed. 673175164Sjhb */ 674185533Skan if (foff >= shmfd->shm_size || 675185533Skan foff + objsize > round_page(shmfd->shm_size)) 676175164Sjhb return (EINVAL); 677175164Sjhb 678175164Sjhb mtx_lock(&shm_timestamp_lock); 679175164Sjhb vfs_timestamp(&shmfd->shm_atime); 680175164Sjhb mtx_unlock(&shm_timestamp_lock); 681175164Sjhb vm_object_reference(shmfd->shm_object); 682175164Sjhb *obj = shmfd->shm_object; 683175164Sjhb return (0); 684175164Sjhb} 685224914Skib 686224914Skibstatic int 687224914Skibshm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 688224914Skib struct thread *td) 689224914Skib{ 690224914Skib struct shmfd *shmfd; 691224914Skib int error; 692224914Skib 693224914Skib error = 0; 694224914Skib shmfd = fp->f_data; 695224914Skib mtx_lock(&shm_timestamp_lock); 696224914Skib /* 697224914Skib * SUSv4 says that x bits of permission need not be affected. 698224914Skib * Be consistent with our shm_open there. 699224914Skib */ 700224914Skib#ifdef MAC 701224914Skib error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 702224914Skib if (error != 0) 703224914Skib goto out; 704224914Skib#endif 705224914Skib error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 706224914Skib shmfd->shm_gid, VADMIN, active_cred, NULL); 707224914Skib if (error != 0) 708224914Skib goto out; 709224914Skib shmfd->shm_mode = mode & ACCESSPERMS; 710224914Skibout: 711224914Skib mtx_unlock(&shm_timestamp_lock); 712224914Skib return (error); 713224914Skib} 714224914Skib 715224914Skibstatic int 716224914Skibshm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 717224914Skib struct thread *td) 718224914Skib{ 719224914Skib struct shmfd *shmfd; 720224914Skib int error; 721224914Skib 722224935Skib error = 0; 723224914Skib shmfd = fp->f_data; 724224914Skib mtx_lock(&shm_timestamp_lock); 725224914Skib#ifdef MAC 726224914Skib error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 727224914Skib if (error != 0) 728224914Skib goto out; 729224914Skib#endif 730224914Skib if (uid == (uid_t)-1) 731224914Skib uid = shmfd->shm_uid; 732224914Skib if (gid == (gid_t)-1) 733224914Skib gid = shmfd->shm_gid; 734224914Skib if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 735224914Skib (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 736224914Skib (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0))) 737224914Skib goto out; 738224914Skib shmfd->shm_uid = uid; 739224914Skib shmfd->shm_gid = gid; 740224914Skibout: 741224914Skib mtx_unlock(&shm_timestamp_lock); 742224914Skib return (error); 743224914Skib} 744228509Sjhb 745228509Sjhb/* 746228509Sjhb * Helper routines to allow the backing object of a shared memory file 747228509Sjhb * descriptor to be mapped in the kernel. 748228509Sjhb */ 749228509Sjhbint 750228509Sjhbshm_map(struct file *fp, size_t size, off_t offset, void **memp) 751228509Sjhb{ 752228509Sjhb struct shmfd *shmfd; 753228509Sjhb vm_offset_t kva, ofs; 754228509Sjhb vm_object_t obj; 755228509Sjhb int rv; 756228509Sjhb 757228509Sjhb if (fp->f_type != DTYPE_SHM) 758228509Sjhb return (EINVAL); 759228509Sjhb shmfd = fp->f_data; 760228509Sjhb obj = shmfd->shm_object; 761248084Sattilio VM_OBJECT_WLOCK(obj); 762228509Sjhb /* 763228509Sjhb * XXXRW: This validation is probably insufficient, and subject to 764228509Sjhb * sign errors. It should be fixed. 765228509Sjhb */ 766228509Sjhb if (offset >= shmfd->shm_size || 767228509Sjhb offset + size > round_page(shmfd->shm_size)) { 768248084Sattilio VM_OBJECT_WUNLOCK(obj); 769228509Sjhb return (EINVAL); 770228509Sjhb } 771228509Sjhb 772228509Sjhb shmfd->shm_kmappings++; 773228509Sjhb vm_object_reference_locked(obj); 774248084Sattilio VM_OBJECT_WUNLOCK(obj); 775228509Sjhb 776228509Sjhb /* Map the object into the kernel_map and wire it. */ 777228509Sjhb kva = vm_map_min(kernel_map); 778228509Sjhb ofs = offset & PAGE_MASK; 779228509Sjhb offset = trunc_page(offset); 780228509Sjhb size = round_page(size + ofs); 781228509Sjhb rv = vm_map_find(kernel_map, obj, offset, &kva, size, 782253620Sjhb VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 783228509Sjhb VM_PROT_READ | VM_PROT_WRITE, 0); 784228509Sjhb if (rv == KERN_SUCCESS) { 785228509Sjhb rv = vm_map_wire(kernel_map, kva, kva + size, 786228509Sjhb VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 787228509Sjhb if (rv == KERN_SUCCESS) { 788228509Sjhb *memp = (void *)(kva + ofs); 789228509Sjhb return (0); 790228509Sjhb } 791228509Sjhb vm_map_remove(kernel_map, kva, kva + size); 792228509Sjhb } else 793228509Sjhb vm_object_deallocate(obj); 794228509Sjhb 795228509Sjhb /* On failure, drop our mapping reference. */ 796248084Sattilio VM_OBJECT_WLOCK(obj); 797228509Sjhb shmfd->shm_kmappings--; 798248084Sattilio VM_OBJECT_WUNLOCK(obj); 799228509Sjhb 800228533Sjhb return (vm_mmap_to_errno(rv)); 801228509Sjhb} 802228509Sjhb 803228509Sjhb/* 804228509Sjhb * We require the caller to unmap the entire entry. This allows us to 805228509Sjhb * safely decrement shm_kmappings when a mapping is removed. 806228509Sjhb */ 807228509Sjhbint 808228509Sjhbshm_unmap(struct file *fp, void *mem, size_t size) 809228509Sjhb{ 810228509Sjhb struct shmfd *shmfd; 811228509Sjhb vm_map_entry_t entry; 812228509Sjhb vm_offset_t kva, ofs; 813228509Sjhb vm_object_t obj; 814228509Sjhb vm_pindex_t pindex; 815228509Sjhb vm_prot_t prot; 816228509Sjhb boolean_t wired; 817228509Sjhb vm_map_t map; 818228509Sjhb int rv; 819228509Sjhb 820228509Sjhb if (fp->f_type != DTYPE_SHM) 821228509Sjhb return (EINVAL); 822228509Sjhb shmfd = fp->f_data; 823228509Sjhb kva = (vm_offset_t)mem; 824228509Sjhb ofs = kva & PAGE_MASK; 825228509Sjhb kva = trunc_page(kva); 826228509Sjhb size = round_page(size + ofs); 827228509Sjhb map = kernel_map; 828228509Sjhb rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 829228509Sjhb &obj, &pindex, &prot, &wired); 830228509Sjhb if (rv != KERN_SUCCESS) 831228509Sjhb return (EINVAL); 832228509Sjhb if (entry->start != kva || entry->end != kva + size) { 833228509Sjhb vm_map_lookup_done(map, entry); 834228509Sjhb return (EINVAL); 835228509Sjhb } 836228509Sjhb vm_map_lookup_done(map, entry); 837228509Sjhb if (obj != shmfd->shm_object) 838228509Sjhb return (EINVAL); 839228509Sjhb vm_map_remove(map, kva, kva + size); 840248084Sattilio VM_OBJECT_WLOCK(obj); 841228509Sjhb KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 842228509Sjhb shmfd->shm_kmappings--; 843248084Sattilio VM_OBJECT_WUNLOCK(obj); 844228509Sjhb return (0); 845228509Sjhb} 846233760Sjhb 847233760Sjhbvoid 848233760Sjhbshm_path(struct shmfd *shmfd, char *path, size_t size) 849233760Sjhb{ 850233760Sjhb 851233760Sjhb if (shmfd->shm_path == NULL) 852233760Sjhb return; 853233760Sjhb sx_slock(&shm_dict_lock); 854233760Sjhb if (shmfd->shm_path != NULL) 855233760Sjhb strlcpy(path, shmfd->shm_path, size); 856233760Sjhb sx_sunlock(&shm_dict_lock); 857233760Sjhb} 858