diff --git a/sys/kern/uipc_shm.c b/sys/kern/uipc_shm.c
index 14fe43524935..1136f34a6f85 100644
--- a/sys/kern/uipc_shm.c
+++ b/sys/kern/uipc_shm.c
@@ -1,2193 +1,2195 @@
/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2006, 2011, 2016-2017 Robert N. M. Watson
* Copyright 2020 The FreeBSD Foundation
* All rights reserved.
*
* Portions of this software were developed by BAE Systems, the University of
* Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL
* contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent
* Computing (TC) research program.
*
* Portions of this software were developed by Konstantin Belousov
* under sponsorship from the FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* Support for shared swap-backed anonymous memory objects via
* shm_open(2), shm_rename(2), and shm_unlink(2).
* While most of the implementation is here, vm_mmap.c contains
* mapping logic changes.
*
* posixshmcontrol(1) allows users to inspect the state of the memory
* objects. Per-uid swap resource limit controls total amount of
* memory that user can consume for anonymous objects, including
* shared.
*/
#include <sys/cdefs.h>
#include "opt_capsicum.h"
#include "opt_ktrace.h"
#include <sys/param.h>
#include <sys/capsicum.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/filio.h>
#include <sys/fnv_hash.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/uio.h>
#include <sys/signal.h>
#include <sys/jail.h>
#include <sys/ktrace.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/mutex.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/refcount.h>
#include <sys/resourcevar.h>
#include <sys/rwlock.h>
#include <sys/sbuf.h>
#include <sys/stat.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#include <sys/sysproto.h>
#include <sys/systm.h>
#include <sys/sx.h>
#include <sys/time.h>
#include <sys/vmmeter.h>
#include <sys/vnode.h>
#include <sys/unistd.h>
#include <sys/user.h>
#include <security/audit/audit.h>
#include <security/mac/mac_framework.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_extern.h>
#include <vm/vm_map.h>
#include <vm/vm_kern.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_pager.h>
#include <vm/swap_pager.h>
struct shm_mapping {
char *sm_path;
Fnv32_t sm_fnv;
struct shmfd *sm_shmfd;
LIST_ENTRY(shm_mapping) sm_link;
};
static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor");
static LIST_HEAD(, shm_mapping) *shm_dictionary;
static struct sx shm_dict_lock;
static struct mtx shm_timestamp_lock;
static u_long shm_hash;
static struct unrhdr64 shm_ino_unr;
static dev_t shm_dev_ino;
#define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash])
static void shm_init(void *arg);
static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd);
static struct shmfd *shm_lookup(char *path, Fnv32_t fnv);
static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
static void shm_doremove(struct shm_mapping *map);
static int shm_dotruncate_cookie(struct shmfd *shmfd, off_t length,
void *rl_cookie);
static int shm_dotruncate_locked(struct shmfd *shmfd, off_t length,
void *rl_cookie);
static int shm_copyin_path(struct thread *td, const char *userpath_in,
char **path_out);
static int shm_deallocate(struct shmfd *shmfd, off_t *offset,
off_t *length, int flags);
static fo_rdwr_t shm_read;
static fo_rdwr_t shm_write;
static fo_truncate_t shm_truncate;
static fo_ioctl_t shm_ioctl;
static fo_stat_t shm_stat;
static fo_close_t shm_close;
static fo_chmod_t shm_chmod;
static fo_chown_t shm_chown;
static fo_seek_t shm_seek;
static fo_fill_kinfo_t shm_fill_kinfo;
static fo_mmap_t shm_mmap;
static fo_get_seals_t shm_get_seals;
static fo_add_seals_t shm_add_seals;
static fo_fallocate_t shm_fallocate;
static fo_fspacectl_t shm_fspacectl;
/* File descriptor operations. */
struct fileops shm_ops = {
.fo_read = shm_read,
.fo_write = shm_write,
.fo_truncate = shm_truncate,
.fo_ioctl = shm_ioctl,
.fo_poll = invfo_poll,
.fo_kqfilter = invfo_kqfilter,
.fo_stat = shm_stat,
.fo_close = shm_close,
.fo_chmod = shm_chmod,
.fo_chown = shm_chown,
.fo_sendfile = vn_sendfile,
.fo_seek = shm_seek,
.fo_fill_kinfo = shm_fill_kinfo,
.fo_mmap = shm_mmap,
.fo_get_seals = shm_get_seals,
.fo_add_seals = shm_add_seals,
.fo_fallocate = shm_fallocate,
.fo_fspacectl = shm_fspacectl,
.fo_cmp = file_kcmp_generic,
.fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE,
};
FEATURE(posix_shm, "POSIX shared memory");
static SYSCTL_NODE(_vm, OID_AUTO, largepages, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
"");
static int largepage_reclaim_tries = 1;
SYSCTL_INT(_vm_largepages, OID_AUTO, reclaim_tries,
CTLFLAG_RWTUN, &largepage_reclaim_tries, 0,
"Number of contig reclaims before giving up for default alloc policy");
#define shm_rangelock_unlock(shmfd, cookie) \
rangelock_unlock(&(shmfd)->shm_rl, (cookie), &(shmfd)->shm_mtx)
#define shm_rangelock_rlock(shmfd, start, end) \
rangelock_rlock(&(shmfd)->shm_rl, (start), (end), &(shmfd)->shm_mtx)
#define shm_rangelock_tryrlock(shmfd, start, end) \
rangelock_tryrlock(&(shmfd)->shm_rl, (start), (end), &(shmfd)->shm_mtx)
#define shm_rangelock_wlock(shmfd, start, end) \
rangelock_wlock(&(shmfd)->shm_rl, (start), (end), &(shmfd)->shm_mtx)
static int
uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio)
{
vm_page_t m;
vm_pindex_t idx;
size_t tlen;
int error, offset, rv;
idx = OFF_TO_IDX(uio->uio_offset);
offset = uio->uio_offset & PAGE_MASK;
tlen = MIN(PAGE_SIZE - offset, len);
rv = vm_page_grab_valid_unlocked(&m, obj, idx,
VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY | VM_ALLOC_NOCREAT);
if (rv == VM_PAGER_OK)
goto found;
/*
* Read I/O without either a corresponding resident page or swap
* page: use zero_region. This is intended to avoid instantiating
* pages on read from a sparse region.
*/
VM_OBJECT_WLOCK(obj);
m = vm_page_lookup(obj, idx);
if (uio->uio_rw == UIO_READ && m == NULL &&
!vm_pager_has_page(obj, idx, NULL, NULL)) {
VM_OBJECT_WUNLOCK(obj);
return (uiomove(__DECONST(void *, zero_region), tlen, uio));
}
/*
* Although the tmpfs vnode lock is held here, it is
* nonetheless safe to sleep waiting for a free page. The
* pageout daemon does not need to acquire the tmpfs vnode
* lock to page out tobj's pages because tobj is a OBJT_SWAP
* type object.
*/
rv = vm_page_grab_valid(&m, obj, idx,
VM_ALLOC_NORMAL | VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY);
if (rv != VM_PAGER_OK) {
VM_OBJECT_WUNLOCK(obj);
if (bootverbose) {
printf("uiomove_object: vm_obj %p idx %jd "
"pager error %d\n", obj, idx, rv);
}
return (rv == VM_PAGER_AGAIN ? ENOSPC : EIO);
}
VM_OBJECT_WUNLOCK(obj);
found:
error = uiomove_fromphys(&m, offset, tlen, uio);
if (uio->uio_rw == UIO_WRITE && error == 0)
vm_page_set_dirty(m);
vm_page_activate(m);
vm_page_sunbusy(m);
return (error);
}
int
uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio)
{
ssize_t resid;
size_t len;
int error;
error = 0;
while ((resid = uio->uio_resid) > 0) {
if (obj_size <= uio->uio_offset)
break;
len = MIN(obj_size - uio->uio_offset, resid);
if (len == 0)
break;
error = uiomove_object_page(obj, len, uio);
if (error != 0 || resid == uio->uio_resid)
break;
}
return (error);
}
static u_long count_largepages[MAXPAGESIZES];
static int
shm_largepage_phys_populate(vm_object_t object, vm_pindex_t pidx,
int fault_type, vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last)
{
vm_page_t m __diagused;
int psind;
psind = object->un_pager.phys.data_val;
if (psind == 0 || pidx >= object->size)
return (VM_PAGER_FAIL);
*first = rounddown2(pidx, pagesizes[psind] / PAGE_SIZE);
/*
* We only busy the first page in the superpage run. It is
* useless to busy whole run since we only remove full
* superpage, and it takes too long to busy e.g. 512 * 512 ==
* 262144 pages constituing 1G amd64 superage.
*/
m = vm_page_grab(object, *first, VM_ALLOC_NORMAL | VM_ALLOC_NOCREAT);
MPASS(m != NULL);
*last = *first + atop(pagesizes[psind]) - 1;
return (VM_PAGER_OK);
}
static boolean_t
shm_largepage_phys_haspage(vm_object_t object, vm_pindex_t pindex,
int *before, int *after)
{
int psind;
psind = object->un_pager.phys.data_val;
if (psind == 0 || pindex >= object->size)
return (FALSE);
if (before != NULL) {
*before = pindex - rounddown2(pindex, pagesizes[psind] /
PAGE_SIZE);
}
if (after != NULL) {
*after = roundup2(pindex, pagesizes[psind] / PAGE_SIZE) -
pindex;
}
return (TRUE);
}
static void
shm_largepage_phys_ctor(vm_object_t object, vm_prot_t prot,
vm_ooffset_t foff, struct ucred *cred)
{
}
static void
shm_largepage_phys_dtor(vm_object_t object)
{
int psind;
psind = object->un_pager.phys.data_val;
if (psind != 0) {
atomic_subtract_long(&count_largepages[psind],
object->size / (pagesizes[psind] / PAGE_SIZE));
vm_wire_sub(object->size);
} else {
KASSERT(object->size == 0,
("largepage phys obj %p not initialized bit size %#jx > 0",
object, (uintmax_t)object->size));
}
}
static const struct phys_pager_ops shm_largepage_phys_ops = {
.phys_pg_populate = shm_largepage_phys_populate,
.phys_pg_haspage = shm_largepage_phys_haspage,
.phys_pg_ctor = shm_largepage_phys_ctor,
.phys_pg_dtor = shm_largepage_phys_dtor,
};
bool
shm_largepage(struct shmfd *shmfd)
{
return (shmfd->shm_object->type == OBJT_PHYS);
}
static void
shm_pager_freespace(vm_object_t obj, vm_pindex_t start, vm_size_t size)
{
struct shmfd *shm;
vm_size_t c;
swap_pager_freespace(obj, start, size, &c);
if (c == 0)
return;
shm = obj->un_pager.swp.swp_priv;
if (shm == NULL)
return;
KASSERT(shm->shm_pages >= c,
("shm %p pages %jd free %jd", shm,
(uintmax_t)shm->shm_pages, (uintmax_t)c));
shm->shm_pages -= c;
}
static void
shm_page_inserted(vm_object_t obj, vm_page_t m)
{
struct shmfd *shm;
shm = obj->un_pager.swp.swp_priv;
if (shm == NULL)
return;
if (!vm_pager_has_page(obj, m->pindex, NULL, NULL))
shm->shm_pages += 1;
}
static void
shm_page_removed(vm_object_t obj, vm_page_t m)
{
struct shmfd *shm;
shm = obj->un_pager.swp.swp_priv;
if (shm == NULL)
return;
if (!vm_pager_has_page(obj, m->pindex, NULL, NULL)) {
KASSERT(shm->shm_pages >= 1,
("shm %p pages %jd free 1", shm,
(uintmax_t)shm->shm_pages));
shm->shm_pages -= 1;
}
}
static struct pagerops shm_swap_pager_ops = {
.pgo_kvme_type = KVME_TYPE_SWAP,
.pgo_freespace = shm_pager_freespace,
.pgo_page_inserted = shm_page_inserted,
.pgo_page_removed = shm_page_removed,
};
static int shmfd_pager_type = -1;
static int
shm_seek(struct file *fp, off_t offset, int whence, struct thread *td)
{
struct shmfd *shmfd;
off_t foffset;
int error;
shmfd = fp->f_data;
foffset = foffset_lock(fp, 0);
error = 0;
switch (whence) {
case L_INCR:
if (foffset < 0 ||
(offset > 0 && foffset > OFF_MAX - offset)) {
error = EOVERFLOW;
break;
}
offset += foffset;
break;
case L_XTND:
if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) {
error = EOVERFLOW;
break;
}
offset += shmfd->shm_size;
break;
case L_SET:
break;
default:
error = EINVAL;
}
if (error == 0) {
if (offset < 0 || offset > shmfd->shm_size)
error = EINVAL;
else
td->td_uretoff.tdu_off = offset;
}
foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
return (error);
}
static int
shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
int flags, struct thread *td)
{
struct shmfd *shmfd;
void *rl_cookie;
int error;
shmfd = fp->f_data;
#ifdef MAC
error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd);
if (error)
return (error);
#endif
foffset_lock_uio(fp, uio, flags);
rl_cookie = shm_rangelock_rlock(shmfd, uio->uio_offset,
uio->uio_offset + uio->uio_resid);
error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
shm_rangelock_unlock(shmfd, rl_cookie);
foffset_unlock_uio(fp, uio, flags);
return (error);
}
static int
shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
int flags, struct thread *td)
{
struct shmfd *shmfd;
void *rl_cookie;
int error;
off_t size;
shmfd = fp->f_data;
#ifdef MAC
error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd);
if (error)
return (error);
#endif
if (shm_largepage(shmfd) && shmfd->shm_lp_psind == 0)
return (EINVAL);
foffset_lock_uio(fp, uio, flags);
if (uio->uio_resid > OFF_MAX - uio->uio_offset) {
/*
* Overflow is only an error if we're supposed to expand on
* write. Otherwise, we'll just truncate the write to the
* size of the file, which can only grow up to OFF_MAX.
*/
if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0) {
foffset_unlock_uio(fp, uio, flags);
return (EFBIG);
}
size = shmfd->shm_size;
} else {
size = uio->uio_offset + uio->uio_resid;
}
if ((flags & FOF_OFFSET) == 0)
rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
else
rl_cookie = shm_rangelock_wlock(shmfd, uio->uio_offset, size);
if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) {
error = EPERM;
} else {
error = 0;
if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0 &&
size > shmfd->shm_size) {
error = shm_dotruncate_cookie(shmfd, size, rl_cookie);
}
if (error == 0)
error = uiomove_object(shmfd->shm_object,
shmfd->shm_size, uio);
}
shm_rangelock_unlock(shmfd, rl_cookie);
foffset_unlock_uio(fp, uio, flags);
return (error);
}
static int
shm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
struct thread *td)
{
struct shmfd *shmfd;
#ifdef MAC
int error;
#endif
shmfd = fp->f_data;
#ifdef MAC
error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
if (error)
return (error);
#endif
return (shm_dotruncate(shmfd, length));
}
int
shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred,
struct thread *td)
{
struct shmfd *shmfd;
struct shm_largepage_conf *conf;
void *rl_cookie;
shmfd = fp->f_data;
switch (com) {
case FIONBIO:
case FIOASYNC:
/*
* Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work,
* just like it would on an unlinked regular file
*/
return (0);
case FIOSSHMLPGCNF:
if (!shm_largepage(shmfd))
return (ENOTTY);
conf = data;
if (shmfd->shm_lp_psind != 0 &&
conf->psind != shmfd->shm_lp_psind)
return (EINVAL);
if (conf->psind <= 0 || conf->psind >= MAXPAGESIZES ||
pagesizes[conf->psind] == 0)
return (EINVAL);
if (conf->alloc_policy != SHM_LARGEPAGE_ALLOC_DEFAULT &&
conf->alloc_policy != SHM_LARGEPAGE_ALLOC_NOWAIT &&
conf->alloc_policy != SHM_LARGEPAGE_ALLOC_HARD)
return (EINVAL);
rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
shmfd->shm_lp_psind = conf->psind;
shmfd->shm_lp_alloc_policy = conf->alloc_policy;
shmfd->shm_object->un_pager.phys.data_val = conf->psind;
shm_rangelock_unlock(shmfd, rl_cookie);
return (0);
case FIOGSHMLPGCNF:
if (!shm_largepage(shmfd))
return (ENOTTY);
conf = data;
rl_cookie = shm_rangelock_rlock(shmfd, 0, OFF_MAX);
conf->psind = shmfd->shm_lp_psind;
conf->alloc_policy = shmfd->shm_lp_alloc_policy;
shm_rangelock_unlock(shmfd, rl_cookie);
return (0);
default:
return (ENOTTY);
}
}
static int
shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred)
{
struct shmfd *shmfd;
#ifdef MAC
int error;
#endif
shmfd = fp->f_data;
#ifdef MAC
error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
if (error)
return (error);
#endif
/*
* Attempt to return sanish values for fstat() on a memory file
* descriptor.
*/
bzero(sb, sizeof(*sb));
sb->st_blksize = PAGE_SIZE;
sb->st_size = shmfd->shm_size;
mtx_lock(&shm_timestamp_lock);
sb->st_atim = shmfd->shm_atime;
sb->st_ctim = shmfd->shm_ctime;
sb->st_mtim = shmfd->shm_mtime;
sb->st_birthtim = shmfd->shm_birthtime;
sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */
sb->st_uid = shmfd->shm_uid;
sb->st_gid = shmfd->shm_gid;
mtx_unlock(&shm_timestamp_lock);
sb->st_dev = shm_dev_ino;
sb->st_ino = shmfd->shm_ino;
sb->st_nlink = shmfd->shm_object->ref_count;
if (shm_largepage(shmfd)) {
sb->st_blocks = shmfd->shm_object->size /
(pagesizes[shmfd->shm_lp_psind] >> PAGE_SHIFT);
} else {
sb->st_blocks = shmfd->shm_pages;
}
return (0);
}
static int
shm_close(struct file *fp, struct thread *td)
{
struct shmfd *shmfd;
shmfd = fp->f_data;
fp->f_data = NULL;
shm_drop(shmfd);
return (0);
}
static int
shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) {
int error;
char *path;
const char *pr_path;
size_t pr_pathlen;
path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
pr_path = td->td_ucred->cr_prison->pr_path;
/* Construct a full pathname for jailed callers. */
pr_pathlen = strcmp(pr_path, "/") ==
0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN);
error = copyinstr(userpath_in, path + pr_pathlen,
MAXPATHLEN - pr_pathlen, NULL);
if (error != 0)
goto out;
#ifdef KTRACE
if (KTRPOINT(curthread, KTR_NAMEI))
ktrnamei(path);
#endif
/* Require paths to start with a '/' character. */
if (path[pr_pathlen] != '/') {
error = EINVAL;
goto out;
}
*path_out = path;
out:
if (error != 0)
free(path, M_SHMFD);
return (error);
}
static int
shm_partial_page_invalidate(vm_object_t object, vm_pindex_t idx, int base,
int end)
{
vm_page_t m;
int rv;
VM_OBJECT_ASSERT_WLOCKED(object);
KASSERT(base >= 0, ("%s: base %d", __func__, base));
KASSERT(end - base <= PAGE_SIZE, ("%s: base %d end %d", __func__, base,
end));
retry:
m = vm_page_grab(object, idx, VM_ALLOC_NOCREAT);
if (m != NULL) {
MPASS(vm_page_all_valid(m));
} else if (vm_pager_has_page(object, idx, NULL, NULL)) {
m = vm_page_alloc(object, idx,
VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL);
if (m == NULL)
goto retry;
vm_object_pip_add(object, 1);
VM_OBJECT_WUNLOCK(object);
rv = vm_pager_get_pages(object, &m, 1, NULL, NULL);
VM_OBJECT_WLOCK(object);
vm_object_pip_wakeup(object);
if (rv == VM_PAGER_OK) {
/*
* Since the page was not resident, and therefore not
* recently accessed, immediately enqueue it for
* asynchronous laundering. The current operation is
* not regarded as an access.
*/
vm_page_launder(m);
} else {
vm_page_free(m);
VM_OBJECT_WUNLOCK(object);
return (EIO);
}
}
if (m != NULL) {
pmap_zero_page_area(m, base, end - base);
KASSERT(vm_page_all_valid(m), ("%s: page %p is invalid",
__func__, m));
vm_page_set_dirty(m);
vm_page_xunbusy(m);
}
return (0);
}
static int
shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie)
{
vm_object_t object;
vm_pindex_t nobjsize;
vm_ooffset_t delta;
int base, error;
KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
object = shmfd->shm_object;
VM_OBJECT_ASSERT_WLOCKED(object);
rangelock_cookie_assert(rl_cookie, RA_WLOCKED);
if (length == shmfd->shm_size)
return (0);
nobjsize = OFF_TO_IDX(length + PAGE_MASK);
/* Are we shrinking? If so, trim the end. */
if (length < shmfd->shm_size) {
if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0)
return (EPERM);
/*
* Disallow any requests to shrink the size if this
* object is mapped into the kernel.
*/
if (shmfd->shm_kmappings > 0)
return (EBUSY);
/*
* Zero the truncated part of the last page.
*/
base = length & PAGE_MASK;
if (base != 0) {
error = shm_partial_page_invalidate(object,
OFF_TO_IDX(length), base, PAGE_SIZE);
if (error)
return (error);
}
delta = IDX_TO_OFF(object->size - nobjsize);
if (nobjsize < object->size)
vm_object_page_remove(object, nobjsize, object->size,
0);
/* Free the swap accounted for shm */
swap_release_by_cred(delta, object->cred);
object->charge -= delta;
} else {
if ((shmfd->shm_seals & F_SEAL_GROW) != 0)
return (EPERM);
/* Try to reserve additional swap space. */
delta = IDX_TO_OFF(nobjsize - object->size);
if (!swap_reserve_by_cred(delta, object->cred))
return (ENOMEM);
object->charge += delta;
}
shmfd->shm_size = length;
mtx_lock(&shm_timestamp_lock);
vfs_timestamp(&shmfd->shm_ctime);
shmfd->shm_mtime = shmfd->shm_ctime;
mtx_unlock(&shm_timestamp_lock);
object->size = nobjsize;
return (0);
}
static int
shm_dotruncate_largepage(struct shmfd *shmfd, off_t length, void *rl_cookie)
{
vm_object_t object;
vm_page_t m;
vm_pindex_t newobjsz;
vm_pindex_t oldobjsz __unused;
int aflags, error, i, psind, try;
KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
object = shmfd->shm_object;
VM_OBJECT_ASSERT_WLOCKED(object);
rangelock_cookie_assert(rl_cookie, RA_WLOCKED);
oldobjsz = object->size;
newobjsz = OFF_TO_IDX(length);
if (length == shmfd->shm_size)
return (0);
psind = shmfd->shm_lp_psind;
if (psind == 0 && length != 0)
return (EINVAL);
if ((length & (pagesizes[psind] - 1)) != 0)
return (EINVAL);
if (length < shmfd->shm_size) {
if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0)
return (EPERM);
if (shmfd->shm_kmappings > 0)
return (EBUSY);
return (ENOTSUP); /* Pages are unmanaged. */
#if 0
vm_object_page_remove(object, newobjsz, oldobjsz, 0);
object->size = newobjsz;
shmfd->shm_size = length;
return (0);
#endif
}
if ((shmfd->shm_seals & F_SEAL_GROW) != 0)
return (EPERM);
aflags = VM_ALLOC_NORMAL | VM_ALLOC_ZERO;
if (shmfd->shm_lp_alloc_policy == SHM_LARGEPAGE_ALLOC_NOWAIT)
aflags |= VM_ALLOC_WAITFAIL;
try = 0;
/*
* Extend shmfd and object, keeping all already fully
* allocated large pages intact even on error, because dropped
* object lock might allowed mapping of them.
*/
while (object->size < newobjsz) {
m = vm_page_alloc_contig(object, object->size, aflags,
pagesizes[psind] / PAGE_SIZE, 0, ~0,
pagesizes[psind], 0,
VM_MEMATTR_DEFAULT);
if (m == NULL) {
VM_OBJECT_WUNLOCK(object);
if (shmfd->shm_lp_alloc_policy ==
SHM_LARGEPAGE_ALLOC_NOWAIT ||
(shmfd->shm_lp_alloc_policy ==
SHM_LARGEPAGE_ALLOC_DEFAULT &&
try >= largepage_reclaim_tries)) {
VM_OBJECT_WLOCK(object);
return (ENOMEM);
}
error = vm_page_reclaim_contig(aflags,
pagesizes[psind] / PAGE_SIZE, 0, ~0,
pagesizes[psind], 0);
if (error == ENOMEM)
error = vm_wait_intr(object);
if (error != 0) {
VM_OBJECT_WLOCK(object);
return (error);
}
try++;
VM_OBJECT_WLOCK(object);
continue;
}
try = 0;
for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) {
if ((m[i].flags & PG_ZERO) == 0)
pmap_zero_page(&m[i]);
vm_page_valid(&m[i]);
vm_page_xunbusy(&m[i]);
}
object->size += OFF_TO_IDX(pagesizes[psind]);
shmfd->shm_size += pagesizes[psind];
atomic_add_long(&count_largepages[psind], 1);
vm_wire_add(atop(pagesizes[psind]));
}
return (0);
}
static int
shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie)
{
int error;
VM_OBJECT_WLOCK(shmfd->shm_object);
error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd,
length, rl_cookie) : shm_dotruncate_locked(shmfd, length,
rl_cookie);
VM_OBJECT_WUNLOCK(shmfd->shm_object);
return (error);
}
int
shm_dotruncate(struct shmfd *shmfd, off_t length)
{
void *rl_cookie;
int error;
rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
error = shm_dotruncate_cookie(shmfd, length, rl_cookie);
shm_rangelock_unlock(shmfd, rl_cookie);
return (error);
}
/*
* shmfd object management including creation and reference counting
* routines.
*/
struct shmfd *
shm_alloc(struct ucred *ucred, mode_t mode, bool largepage)
{
struct shmfd *shmfd;
vm_object_t obj;
shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
shmfd->shm_size = 0;
shmfd->shm_uid = ucred->cr_uid;
shmfd->shm_gid = ucred->cr_gid;
shmfd->shm_mode = mode;
if (largepage) {
shmfd->shm_object = phys_pager_allocate(NULL,
&shm_largepage_phys_ops, NULL, shmfd->shm_size,
VM_PROT_DEFAULT, 0, ucred);
shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT;
} else {
obj = vm_pager_allocate(shmfd_pager_type, NULL,
shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred);
VM_OBJECT_WLOCK(obj);
obj->un_pager.swp.swp_priv = shmfd;
VM_OBJECT_WUNLOCK(obj);
shmfd->shm_object = obj;
}
KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate"));
vfs_timestamp(&shmfd->shm_birthtime);
shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
shmfd->shm_birthtime;
shmfd->shm_ino = alloc_unr64(&shm_ino_unr);
refcount_init(&shmfd->shm_refs, 1);
mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF);
rangelock_init(&shmfd->shm_rl);
#ifdef MAC
mac_posixshm_init(shmfd);
mac_posixshm_create(ucred, shmfd);
#endif
return (shmfd);
}
struct shmfd *
shm_hold(struct shmfd *shmfd)
{
refcount_acquire(&shmfd->shm_refs);
return (shmfd);
}
void
shm_drop(struct shmfd *shmfd)
{
vm_object_t obj;
if (refcount_release(&shmfd->shm_refs)) {
#ifdef MAC
mac_posixshm_destroy(shmfd);
#endif
rangelock_destroy(&shmfd->shm_rl);
mtx_destroy(&shmfd->shm_mtx);
obj = shmfd->shm_object;
if (!shm_largepage(shmfd)) {
VM_OBJECT_WLOCK(obj);
obj->un_pager.swp.swp_priv = NULL;
VM_OBJECT_WUNLOCK(obj);
}
vm_object_deallocate(obj);
free(shmfd, M_SHMFD);
}
}
/*
* Determine if the credentials have sufficient permissions for a
* specified combination of FREAD and FWRITE.
*/
int
shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
{
accmode_t accmode;
int error;
accmode = 0;
if (flags & FREAD)
accmode |= VREAD;
if (flags & FWRITE)
accmode |= VWRITE;
mtx_lock(&shm_timestamp_lock);
error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
accmode, ucred);
mtx_unlock(&shm_timestamp_lock);
return (error);
}
static void
shm_init(void *arg)
{
char name[32];
int i;
mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
sx_init(&shm_dict_lock, "shm dictionary");
shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
new_unrhdr64(&shm_ino_unr, 1);
shm_dev_ino = devfs_alloc_cdp_inode();
KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized"));
shmfd_pager_type = vm_pager_alloc_dyn_type(&shm_swap_pager_ops,
OBJT_SWAP);
MPASS(shmfd_pager_type != -1);
for (i = 1; i < MAXPAGESIZES; i++) {
if (pagesizes[i] == 0)
break;
#define M (1024 * 1024)
#define G (1024 * M)
if (pagesizes[i] >= G)
snprintf(name, sizeof(name), "%luG", pagesizes[i] / G);
else if (pagesizes[i] >= M)
snprintf(name, sizeof(name), "%luM", pagesizes[i] / M);
else
snprintf(name, sizeof(name), "%lu", pagesizes[i]);
#undef G
#undef M
SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages),
OID_AUTO, name, CTLFLAG_RD, &count_largepages[i],
"number of non-transient largepages allocated");
}
}
SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL);
/*
* Remove all shared memory objects that belong to a prison.
*/
void
shm_remove_prison(struct prison *pr)
{
struct shm_mapping *shmm, *tshmm;
u_long i;
sx_xlock(&shm_dict_lock);
for (i = 0; i < shm_hash + 1; i++) {
LIST_FOREACH_SAFE(shmm, &shm_dictionary[i], sm_link, tshmm) {
if (shmm->sm_shmfd->shm_object->cred &&
shmm->sm_shmfd->shm_object->cred->cr_prison == pr)
shm_doremove(shmm);
}
}
sx_xunlock(&shm_dict_lock);
}
/*
* Dictionary management. We maintain an in-kernel dictionary to map
* paths to shmfd objects. We use the FNV hash on the path to store
* the mappings in a hash table.
*/
static struct shmfd *
shm_lookup(char *path, Fnv32_t fnv)
{
struct shm_mapping *map;
LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
if (map->sm_fnv != fnv)
continue;
if (strcmp(map->sm_path, path) == 0)
return (map->sm_shmfd);
}
return (NULL);
}
static void
shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
{
struct shm_mapping *map;
map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
map->sm_path = path;
map->sm_fnv = fnv;
map->sm_shmfd = shm_hold(shmfd);
shmfd->shm_path = path;
LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
}
static int
shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
{
struct shm_mapping *map;
int error;
LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
if (map->sm_fnv != fnv)
continue;
if (strcmp(map->sm_path, path) == 0) {
#ifdef MAC
error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
if (error)
return (error);
#endif
error = shm_access(map->sm_shmfd, ucred,
FREAD | FWRITE);
if (error)
return (error);
shm_doremove(map);
return (0);
}
}
return (ENOENT);
}
static void
shm_doremove(struct shm_mapping *map)
{
map->sm_shmfd->shm_path = NULL;
LIST_REMOVE(map, sm_link);
shm_drop(map->sm_shmfd);
free(map->sm_path, M_SHMFD);
free(map, M_SHMFD);
}
int
kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode,
int shmflags, struct filecaps *fcaps, const char *name __unused)
{
struct pwddesc *pdp;
struct shmfd *shmfd;
struct file *fp;
char *path;
void *rl_cookie;
Fnv32_t fnv;
mode_t cmode;
int error, fd, initial_seals;
bool largepage;
if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE |
SHM_LARGEPAGE)) != 0)
return (EINVAL);
initial_seals = F_SEAL_SEAL;
if ((shmflags & SHM_ALLOW_SEALING) != 0)
initial_seals &= ~F_SEAL_SEAL;
AUDIT_ARG_FFLAGS(flags);
AUDIT_ARG_MODE(mode);
if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR)
return (EINVAL);
if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0)
return (EINVAL);
largepage = (shmflags & SHM_LARGEPAGE) != 0;
if (largepage && !PMAP_HAS_LARGEPAGES)
return (ENOTTY);
/*
* Currently only F_SEAL_SEAL may be set when creating or opening shmfd.
* If the decision is made later to allow additional seals, care must be
* taken below to ensure that the seals are properly set if the shmfd
* already existed -- this currently assumes that only F_SEAL_SEAL can
* be set and doesn't take further precautions to ensure the validity of
* the seals being added with respect to current mappings.
*/
if ((initial_seals & ~F_SEAL_SEAL) != 0)
return (EINVAL);
if (userpath != SHM_ANON) {
error = shm_copyin_path(td, userpath, &path);
if (error != 0)
return (error);
#ifdef CAPABILITY_MODE
/*
* shm_open(2) is only allowed for anonymous objects.
*/
if (CAP_TRACING(td))
ktrcapfail(CAPFAIL_NAMEI, path);
if (IN_CAPABILITY_MODE(td)) {
free(path, M_SHMFD);
return (ECAPMODE);
}
#endif
AUDIT_ARG_UPATH1_CANON(path);
+ } else {
+ path = NULL;
}
pdp = td->td_proc->p_pd;
cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS;
/*
* shm_open(2) created shm should always have O_CLOEXEC set, as mandated
* by POSIX. We allow it to be unset here so that an in-kernel
* interface may be written as a thin layer around shm, optionally not
* setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally
* in sys_shm_open() to keep this implementation compliant.
*/
error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps);
if (error) {
free(path, M_SHMFD);
return (error);
}
/* A SHM_ANON path pointer creates an anonymous object. */
if (userpath == SHM_ANON) {
/* A read-only anonymous object is pointless. */
if ((flags & O_ACCMODE) == O_RDONLY) {
fdclose(td, fp, fd);
fdrop(fp, td);
return (EINVAL);
}
shmfd = shm_alloc(td->td_ucred, cmode, largepage);
shmfd->shm_seals = initial_seals;
shmfd->shm_flags = shmflags;
} else {
fnv = fnv_32_str(path, FNV1_32_INIT);
sx_xlock(&shm_dict_lock);
shmfd = shm_lookup(path, fnv);
if (shmfd == NULL) {
/* Object does not yet exist, create it if requested. */
if (flags & O_CREAT) {
#ifdef MAC
error = mac_posixshm_check_create(td->td_ucred,
path);
if (error == 0) {
#endif
shmfd = shm_alloc(td->td_ucred, cmode,
largepage);
shmfd->shm_seals = initial_seals;
shmfd->shm_flags = shmflags;
shm_insert(path, fnv, shmfd);
#ifdef MAC
}
#endif
} else {
free(path, M_SHMFD);
error = ENOENT;
}
} else {
rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
/*
* kern_shm_open() likely shouldn't ever error out on
* trying to set a seal that already exists, unlike
* F_ADD_SEALS. This would break terribly as
* shm_open(2) actually sets F_SEAL_SEAL to maintain
* historical behavior where the underlying file could
* not be sealed.
*/
initial_seals &= ~shmfd->shm_seals;
/*
* Object already exists, obtain a new
* reference if requested and permitted.
*/
free(path, M_SHMFD);
/*
* initial_seals can't set additional seals if we've
* already been set F_SEAL_SEAL. If F_SEAL_SEAL is set,
* then we've already removed that one from
* initial_seals. This is currently redundant as we
* only allow setting F_SEAL_SEAL at creation time, but
* it's cheap to check and decreases the effort required
* to allow additional seals.
*/
if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 &&
initial_seals != 0)
error = EPERM;
else if ((flags & (O_CREAT | O_EXCL)) ==
(O_CREAT | O_EXCL))
error = EEXIST;
else if (shmflags != 0 && shmflags != shmfd->shm_flags)
error = EINVAL;
else {
#ifdef MAC
error = mac_posixshm_check_open(td->td_ucred,
shmfd, FFLAGS(flags & O_ACCMODE));
if (error == 0)
#endif
error = shm_access(shmfd, td->td_ucred,
FFLAGS(flags & O_ACCMODE));
}
/*
* Truncate the file back to zero length if
* O_TRUNC was specified and the object was
* opened with read/write.
*/
if (error == 0 &&
(flags & (O_ACCMODE | O_TRUNC)) ==
(O_RDWR | O_TRUNC)) {
VM_OBJECT_WLOCK(shmfd->shm_object);
#ifdef MAC
error = mac_posixshm_check_truncate(
td->td_ucred, fp->f_cred, shmfd);
if (error == 0)
#endif
error = shm_dotruncate_locked(shmfd, 0,
rl_cookie);
VM_OBJECT_WUNLOCK(shmfd->shm_object);
}
if (error == 0) {
/*
* Currently we only allow F_SEAL_SEAL to be
* set initially. As noted above, this would
* need to be reworked should that change.
*/
shmfd->shm_seals |= initial_seals;
shm_hold(shmfd);
}
shm_rangelock_unlock(shmfd, rl_cookie);
}
sx_xunlock(&shm_dict_lock);
if (error) {
fdclose(td, fp, fd);
fdrop(fp, td);
return (error);
}
}
finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
td->td_retval[0] = fd;
fdrop(fp, td);
return (0);
}
/* System calls. */
#ifdef COMPAT_FREEBSD12
int
freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap)
{
return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC,
uap->mode, NULL));
}
#endif
int
sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
{
char *path;
Fnv32_t fnv;
int error;
error = shm_copyin_path(td, uap->path, &path);
if (error != 0)
return (error);
AUDIT_ARG_UPATH1_CANON(path);
fnv = fnv_32_str(path, FNV1_32_INIT);
sx_xlock(&shm_dict_lock);
error = shm_remove(path, fnv, td->td_ucred);
sx_xunlock(&shm_dict_lock);
free(path, M_SHMFD);
return (error);
}
int
sys_shm_rename(struct thread *td, struct shm_rename_args *uap)
{
char *path_from = NULL, *path_to = NULL;
Fnv32_t fnv_from, fnv_to;
struct shmfd *fd_from;
struct shmfd *fd_to;
int error;
int flags;
flags = uap->flags;
AUDIT_ARG_FFLAGS(flags);
/*
* Make sure the user passed only valid flags.
* If you add a new flag, please add a new term here.
*/
if ((flags & ~(
SHM_RENAME_NOREPLACE |
SHM_RENAME_EXCHANGE
)) != 0) {
error = EINVAL;
goto out;
}
/*
* EXCHANGE and NOREPLACE don't quite make sense together. Let's
* force the user to choose one or the other.
*/
if ((flags & SHM_RENAME_NOREPLACE) != 0 &&
(flags & SHM_RENAME_EXCHANGE) != 0) {
error = EINVAL;
goto out;
}
/* Renaming to or from anonymous makes no sense */
if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) {
error = EINVAL;
goto out;
}
error = shm_copyin_path(td, uap->path_from, &path_from);
if (error != 0)
goto out;
error = shm_copyin_path(td, uap->path_to, &path_to);
if (error != 0)
goto out;
AUDIT_ARG_UPATH1_CANON(path_from);
AUDIT_ARG_UPATH2_CANON(path_to);
/* Rename with from/to equal is a no-op */
if (strcmp(path_from, path_to) == 0)
goto out;
fnv_from = fnv_32_str(path_from, FNV1_32_INIT);
fnv_to = fnv_32_str(path_to, FNV1_32_INIT);
sx_xlock(&shm_dict_lock);
fd_from = shm_lookup(path_from, fnv_from);
if (fd_from == NULL) {
error = ENOENT;
goto out_locked;
}
fd_to = shm_lookup(path_to, fnv_to);
if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) {
error = EEXIST;
goto out_locked;
}
/*
* Unconditionally prevents shm_remove from invalidating the 'from'
* shm's state.
*/
shm_hold(fd_from);
error = shm_remove(path_from, fnv_from, td->td_ucred);
/*
* One of my assumptions failed if ENOENT (e.g. locking didn't
* protect us)
*/
KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s",
path_from));
if (error != 0) {
shm_drop(fd_from);
goto out_locked;
}
/*
* If we are exchanging, we need to ensure the shm_remove below
* doesn't invalidate the dest shm's state.
*/
if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL)
shm_hold(fd_to);
/*
* NOTE: if path_to is not already in the hash, c'est la vie;
* it simply means we have nothing already at path_to to unlink.
* That is the ENOENT case.
*
* If we somehow don't have access to unlink this guy, but
* did for the shm at path_from, then relink the shm to path_from
* and abort with EACCES.
*
* All other errors: that is weird; let's relink and abort the
* operation.
*/
error = shm_remove(path_to, fnv_to, td->td_ucred);
if (error != 0 && error != ENOENT) {
shm_insert(path_from, fnv_from, fd_from);
shm_drop(fd_from);
/* Don't free path_from now, since the hash references it */
path_from = NULL;
goto out_locked;
}
error = 0;
shm_insert(path_to, fnv_to, fd_from);
/* Don't free path_to now, since the hash references it */
path_to = NULL;
/* We kept a ref when we removed, and incremented again in insert */
shm_drop(fd_from);
KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n",
fd_from->shm_refs));
if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) {
shm_insert(path_from, fnv_from, fd_to);
path_from = NULL;
shm_drop(fd_to);
KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n",
fd_to->shm_refs));
}
out_locked:
sx_xunlock(&shm_dict_lock);
out:
free(path_from, M_SHMFD);
free(path_to, M_SHMFD);
return (error);
}
static int
shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr,
vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags,
vm_ooffset_t foff, struct thread *td)
{
struct vmspace *vms;
vm_map_entry_t next_entry, prev_entry;
vm_offset_t align, mask, maxaddr;
int docow, error, rv, try;
bool curmap;
if (shmfd->shm_lp_psind == 0)
return (EINVAL);
/* MAP_PRIVATE is disabled */
if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL |
MAP_NOCORE | MAP_32BIT | MAP_ALIGNMENT_MASK)) != 0)
return (EINVAL);
vms = td->td_proc->p_vmspace;
curmap = map == &vms->vm_map;
if (curmap) {
error = kern_mmap_racct_check(td, map, size);
if (error != 0)
return (error);
}
docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT;
docow |= MAP_INHERIT_SHARE;
if ((flags & MAP_NOCORE) != 0)
docow |= MAP_DISABLE_COREDUMP;
mask = pagesizes[shmfd->shm_lp_psind] - 1;
if ((foff & mask) != 0)
return (EINVAL);
maxaddr = vm_map_max(map);
if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR)
maxaddr = MAP_32BIT_MAX_ADDR;
if (size == 0 || (size & mask) != 0 ||
(*addr != 0 && ((*addr & mask) != 0 ||
*addr + size < *addr || *addr + size > maxaddr)))
return (EINVAL);
align = flags & MAP_ALIGNMENT_MASK;
if (align == 0) {
align = pagesizes[shmfd->shm_lp_psind];
} else if (align == MAP_ALIGNED_SUPER) {
if (shmfd->shm_lp_psind != 1)
return (EINVAL);
align = pagesizes[1];
} else {
align >>= MAP_ALIGNMENT_SHIFT;
align = 1ULL << align;
/* Also handles overflow. */
if (align < pagesizes[shmfd->shm_lp_psind])
return (EINVAL);
}
vm_map_lock(map);
if ((flags & MAP_FIXED) == 0) {
try = 1;
if (curmap && (*addr == 0 ||
(*addr >= round_page((vm_offset_t)vms->vm_taddr) &&
*addr < round_page((vm_offset_t)vms->vm_daddr +
lim_max(td, RLIMIT_DATA))))) {
*addr = roundup2((vm_offset_t)vms->vm_daddr +
lim_max(td, RLIMIT_DATA),
pagesizes[shmfd->shm_lp_psind]);
}
again:
rv = vm_map_find_aligned(map, addr, size, maxaddr, align);
if (rv != KERN_SUCCESS) {
if (try == 1) {
try = 2;
*addr = vm_map_min(map);
if ((*addr & mask) != 0)
*addr = (*addr + mask) & mask;
goto again;
}
goto fail1;
}
} else if ((flags & MAP_EXCL) == 0) {
rv = vm_map_delete(map, *addr, *addr + size);
if (rv != KERN_SUCCESS)
goto fail1;
} else {
error = ENOSPC;
if (vm_map_lookup_entry(map, *addr, &prev_entry))
goto fail;
next_entry = vm_map_entry_succ(prev_entry);
if (next_entry->start < *addr + size)
goto fail;
}
rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size,
prot, max_prot, docow);
fail1:
error = vm_mmap_to_errno(rv);
fail:
vm_map_unlock(map);
return (error);
}
static int
shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize,
vm_prot_t prot, vm_prot_t cap_maxprot, int flags,
vm_ooffset_t foff, struct thread *td)
{
struct shmfd *shmfd;
vm_prot_t maxprot;
int error;
bool writecnt;
void *rl_cookie;
shmfd = fp->f_data;
maxprot = VM_PROT_NONE;
rl_cookie = shm_rangelock_rlock(shmfd, 0, objsize);
/* FREAD should always be set. */
if ((fp->f_flag & FREAD) != 0)
maxprot |= VM_PROT_EXECUTE | VM_PROT_READ;
/*
* If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared
* mapping with a write seal applied. Private mappings are always
* writeable.
*/
if ((flags & MAP_SHARED) == 0) {
cap_maxprot |= VM_PROT_WRITE;
maxprot |= VM_PROT_WRITE;
writecnt = false;
} else {
if ((fp->f_flag & FWRITE) != 0 &&
(shmfd->shm_seals & F_SEAL_WRITE) == 0)
maxprot |= VM_PROT_WRITE;
/*
* Any mappings from a writable descriptor may be upgraded to
* VM_PROT_WRITE with mprotect(2), unless a write-seal was
* applied between the open and subsequent mmap(2). We want to
* reject application of a write seal as long as any such
* mapping exists so that the seal cannot be trivially bypassed.
*/
writecnt = (maxprot & VM_PROT_WRITE) != 0;
if (!writecnt && (prot & VM_PROT_WRITE) != 0) {
error = EACCES;
goto out;
}
}
maxprot &= cap_maxprot;
/* See comment in vn_mmap(). */
if (
#ifdef _LP64
objsize > OFF_MAX ||
#endif
foff > OFF_MAX - objsize) {
error = EINVAL;
goto out;
}
#ifdef MAC
error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags);
if (error != 0)
goto out;
#endif
mtx_lock(&shm_timestamp_lock);
vfs_timestamp(&shmfd->shm_atime);
mtx_unlock(&shm_timestamp_lock);
vm_object_reference(shmfd->shm_object);
if (shm_largepage(shmfd)) {
writecnt = false;
error = shm_mmap_large(shmfd, map, addr, objsize, prot,
maxprot, flags, foff, td);
} else {
if (writecnt) {
vm_pager_update_writecount(shmfd->shm_object, 0,
objsize);
}
error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags,
shmfd->shm_object, foff, writecnt, td);
}
if (error != 0) {
if (writecnt)
vm_pager_release_writecount(shmfd->shm_object, 0,
objsize);
vm_object_deallocate(shmfd->shm_object);
}
out:
shm_rangelock_unlock(shmfd, rl_cookie);
return (error);
}
static int
shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
struct thread *td)
{
struct shmfd *shmfd;
int error;
error = 0;
shmfd = fp->f_data;
mtx_lock(&shm_timestamp_lock);
/*
* SUSv4 says that x bits of permission need not be affected.
* Be consistent with our shm_open there.
*/
#ifdef MAC
error = mac_posixshm_check_setmode(active_cred, shmfd, mode);
if (error != 0)
goto out;
#endif
error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
VADMIN, active_cred);
if (error != 0)
goto out;
shmfd->shm_mode = mode & ACCESSPERMS;
out:
mtx_unlock(&shm_timestamp_lock);
return (error);
}
static int
shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
struct thread *td)
{
struct shmfd *shmfd;
int error;
error = 0;
shmfd = fp->f_data;
mtx_lock(&shm_timestamp_lock);
#ifdef MAC
error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid);
if (error != 0)
goto out;
#endif
if (uid == (uid_t)-1)
uid = shmfd->shm_uid;
if (gid == (gid_t)-1)
gid = shmfd->shm_gid;
if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) ||
(gid != shmfd->shm_gid && !groupmember(gid, active_cred))) &&
(error = priv_check_cred(active_cred, PRIV_VFS_CHOWN)))
goto out;
shmfd->shm_uid = uid;
shmfd->shm_gid = gid;
out:
mtx_unlock(&shm_timestamp_lock);
return (error);
}
/*
* Helper routines to allow the backing object of a shared memory file
* descriptor to be mapped in the kernel.
*/
int
shm_map(struct file *fp, size_t size, off_t offset, void **memp)
{
struct shmfd *shmfd;
vm_offset_t kva, ofs;
vm_object_t obj;
int rv;
if (fp->f_type != DTYPE_SHM)
return (EINVAL);
shmfd = fp->f_data;
obj = shmfd->shm_object;
VM_OBJECT_WLOCK(obj);
/*
* XXXRW: This validation is probably insufficient, and subject to
* sign errors. It should be fixed.
*/
if (offset >= shmfd->shm_size ||
offset + size > round_page(shmfd->shm_size)) {
VM_OBJECT_WUNLOCK(obj);
return (EINVAL);
}
shmfd->shm_kmappings++;
vm_object_reference_locked(obj);
VM_OBJECT_WUNLOCK(obj);
/* Map the object into the kernel_map and wire it. */
kva = vm_map_min(kernel_map);
ofs = offset & PAGE_MASK;
offset = trunc_page(offset);
size = round_page(size + ofs);
rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0,
VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE,
VM_PROT_READ | VM_PROT_WRITE, 0);
if (rv == KERN_SUCCESS) {
rv = vm_map_wire(kernel_map, kva, kva + size,
VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
if (rv == KERN_SUCCESS) {
*memp = (void *)(kva + ofs);
return (0);
}
vm_map_remove(kernel_map, kva, kva + size);
} else
vm_object_deallocate(obj);
/* On failure, drop our mapping reference. */
VM_OBJECT_WLOCK(obj);
shmfd->shm_kmappings--;
VM_OBJECT_WUNLOCK(obj);
return (vm_mmap_to_errno(rv));
}
/*
* We require the caller to unmap the entire entry. This allows us to
* safely decrement shm_kmappings when a mapping is removed.
*/
int
shm_unmap(struct file *fp, void *mem, size_t size)
{
struct shmfd *shmfd;
vm_map_entry_t entry;
vm_offset_t kva, ofs;
vm_object_t obj;
vm_pindex_t pindex;
vm_prot_t prot;
boolean_t wired;
vm_map_t map;
int rv;
if (fp->f_type != DTYPE_SHM)
return (EINVAL);
shmfd = fp->f_data;
kva = (vm_offset_t)mem;
ofs = kva & PAGE_MASK;
kva = trunc_page(kva);
size = round_page(size + ofs);
map = kernel_map;
rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry,
&obj, &pindex, &prot, &wired);
if (rv != KERN_SUCCESS)
return (EINVAL);
if (entry->start != kva || entry->end != kva + size) {
vm_map_lookup_done(map, entry);
return (EINVAL);
}
vm_map_lookup_done(map, entry);
if (obj != shmfd->shm_object)
return (EINVAL);
vm_map_remove(map, kva, kva + size);
VM_OBJECT_WLOCK(obj);
KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped"));
shmfd->shm_kmappings--;
VM_OBJECT_WUNLOCK(obj);
return (0);
}
static int
shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list)
{
const char *path, *pr_path;
size_t pr_pathlen;
bool visible;
sx_assert(&shm_dict_lock, SA_LOCKED);
kif->kf_type = KF_TYPE_SHM;
kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode;
kif->kf_un.kf_file.kf_file_size = shmfd->shm_size;
if (shmfd->shm_path != NULL) {
if (shmfd->shm_path != NULL) {
path = shmfd->shm_path;
pr_path = curthread->td_ucred->cr_prison->pr_path;
if (strcmp(pr_path, "/") != 0) {
/* Return the jail-rooted pathname. */
pr_pathlen = strlen(pr_path);
visible = strncmp(path, pr_path, pr_pathlen)
== 0 && path[pr_pathlen] == '/';
if (list && !visible)
return (EPERM);
if (visible)
path += pr_pathlen;
}
strlcpy(kif->kf_path, path, sizeof(kif->kf_path));
}
}
return (0);
}
static int
shm_fill_kinfo(struct file *fp, struct kinfo_file *kif,
struct filedesc *fdp __unused)
{
int res;
sx_slock(&shm_dict_lock);
res = shm_fill_kinfo_locked(fp->f_data, kif, false);
sx_sunlock(&shm_dict_lock);
return (res);
}
static int
shm_add_seals(struct file *fp, int seals)
{
struct shmfd *shmfd;
void *rl_cookie;
vm_ooffset_t writemappings;
int error, nseals;
error = 0;
shmfd = fp->f_data;
rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
/* Even already-set seals should result in EPERM. */
if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) {
error = EPERM;
goto out;
}
nseals = seals & ~shmfd->shm_seals;
if ((nseals & F_SEAL_WRITE) != 0) {
if (shm_largepage(shmfd)) {
error = ENOTSUP;
goto out;
}
/*
* The rangelock above prevents writable mappings from being
* added after we've started applying seals. The RLOCK here
* is to avoid torn reads on ILP32 arches as unmapping/reducing
* writemappings will be done without a rangelock.
*/
VM_OBJECT_RLOCK(shmfd->shm_object);
writemappings = shmfd->shm_object->un_pager.swp.writemappings;
VM_OBJECT_RUNLOCK(shmfd->shm_object);
/* kmappings are also writable */
if (writemappings > 0) {
error = EBUSY;
goto out;
}
}
shmfd->shm_seals |= nseals;
out:
shm_rangelock_unlock(shmfd, rl_cookie);
return (error);
}
static int
shm_get_seals(struct file *fp, int *seals)
{
struct shmfd *shmfd;
shmfd = fp->f_data;
*seals = shmfd->shm_seals;
return (0);
}
static int
shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t *length, int flags)
{
vm_object_t object;
vm_pindex_t pistart, pi, piend;
vm_ooffset_t off, len;
int startofs, endofs, end;
int error;
off = *offset;
len = *length;
KASSERT(off + len <= (vm_ooffset_t)OFF_MAX, ("off + len overflows"));
if (off + len > shmfd->shm_size)
len = shmfd->shm_size - off;
object = shmfd->shm_object;
startofs = off & PAGE_MASK;
endofs = (off + len) & PAGE_MASK;
pistart = OFF_TO_IDX(off);
piend = OFF_TO_IDX(off + len);
pi = OFF_TO_IDX(off + PAGE_MASK);
error = 0;
/* Handle the case when offset is on or beyond shm size. */
if ((off_t)len <= 0) {
*length = 0;
return (0);
}
VM_OBJECT_WLOCK(object);
if (startofs != 0) {
end = pistart != piend ? PAGE_SIZE : endofs;
error = shm_partial_page_invalidate(object, pistart, startofs,
end);
if (error)
goto out;
off += end - startofs;
len -= end - startofs;
}
if (pi < piend) {
vm_object_page_remove(object, pi, piend, 0);
off += IDX_TO_OFF(piend - pi);
len -= IDX_TO_OFF(piend - pi);
}
if (endofs != 0 && pistart != piend) {
error = shm_partial_page_invalidate(object, piend, 0, endofs);
if (error)
goto out;
off += endofs;
len -= endofs;
}
out:
VM_OBJECT_WUNLOCK(shmfd->shm_object);
*offset = off;
*length = len;
return (error);
}
static int
shm_fspacectl(struct file *fp, int cmd, off_t *offset, off_t *length, int flags,
struct ucred *active_cred, struct thread *td)
{
void *rl_cookie;
struct shmfd *shmfd;
off_t off, len;
int error;
KASSERT(cmd == SPACECTL_DEALLOC, ("shm_fspacectl: Invalid cmd"));
KASSERT((flags & ~SPACECTL_F_SUPPORTED) == 0,
("shm_fspacectl: non-zero flags"));
KASSERT(*offset >= 0 && *length > 0 && *length <= OFF_MAX - *offset,
("shm_fspacectl: offset/length overflow or underflow"));
error = EINVAL;
shmfd = fp->f_data;
off = *offset;
len = *length;
rl_cookie = shm_rangelock_wlock(shmfd, off, off + len);
switch (cmd) {
case SPACECTL_DEALLOC:
if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) {
error = EPERM;
break;
}
error = shm_deallocate(shmfd, &off, &len, flags);
*offset = off;
*length = len;
break;
default:
__assert_unreachable();
}
shm_rangelock_unlock(shmfd, rl_cookie);
return (error);
}
static int
shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td)
{
void *rl_cookie;
struct shmfd *shmfd;
size_t size;
int error;
/* This assumes that the caller already checked for overflow. */
error = 0;
shmfd = fp->f_data;
size = offset + len;
/*
* Just grab the rangelock for the range that we may be attempting to
* grow, rather than blocking read/write for regions we won't be
* touching while this (potential) resize is in progress. Other
* attempts to resize the shmfd will have to take a write lock from 0 to
* OFF_MAX, so this being potentially beyond the current usable range of
* the shmfd is not necessarily a concern. If other mechanisms are
* added to grow a shmfd, this may need to be re-evaluated.
*/
rl_cookie = shm_rangelock_wlock(shmfd, offset, size);
if (size > shmfd->shm_size)
error = shm_dotruncate_cookie(shmfd, size, rl_cookie);
shm_rangelock_unlock(shmfd, rl_cookie);
/* Translate to posix_fallocate(2) return value as needed. */
if (error == ENOMEM)
error = ENOSPC;
return (error);
}
static int
sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS)
{
struct shm_mapping *shmm;
struct sbuf sb;
struct kinfo_file kif;
u_long i;
int error, error2;
sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req);
sbuf_clear_flags(&sb, SBUF_INCLUDENUL);
error = 0;
sx_slock(&shm_dict_lock);
for (i = 0; i < shm_hash + 1; i++) {
LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) {
error = shm_fill_kinfo_locked(shmm->sm_shmfd,
&kif, true);
if (error == EPERM) {
error = 0;
continue;
}
if (error != 0)
break;
pack_kinfo(&kif);
error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ?
0 : ENOMEM;
if (error != 0)
break;
}
}
sx_sunlock(&shm_dict_lock);
error2 = sbuf_finish(&sb);
sbuf_delete(&sb);
return (error != 0 ? error : error2);
}
SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list,
CTLFLAG_RD | CTLFLAG_PRISON | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE,
NULL, 0, sysctl_posix_shm_list, "",
"POSIX SHM list");
int
kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode,
struct filecaps *caps)
{
return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL));
}
/*
* This version of the shm_open() interface leaves CLOEXEC behavior up to the
* caller, and libc will enforce it for the traditional shm_open() call. This
* allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This
* interface also includes a 'name' argument that is currently unused, but could
* potentially be exported later via some interface for debugging purposes.
* From the kernel's perspective, it is optional. Individual consumers like
* memfd_create() may require it in order to be compatible with other systems
* implementing the same function.
*/
int
sys_shm_open2(struct thread *td, struct shm_open2_args *uap)
{
return (kern_shm_open2(td, uap->path, uap->flags, uap->mode,
uap->shmflags, NULL, uap->name));
}