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freebsd-skq/sys/fs/fuse/fuse_vfsops.c
pjd 029a6f5d92 Change the cap_rights_t type from uint64_t to a structure that we can extend 
in the future in a backward compatible (API and ABI) way.

The cap_rights_t represents capability rights. We used to use one bit to
represent one right, but we are running out of spare bits. Currently the new
structure provides place for 114 rights (so 50 more than the previous
cap_rights_t), but it is possible to grow the structure to hold at least 285
rights, although we can make it even larger if 285 rights won't be enough.

The structure definition looks like this:

	struct cap_rights {
		uint64_t	cr_rights[CAP_RIGHTS_VERSION + 2];
	};

The initial CAP_RIGHTS_VERSION is 0.

The top two bits in the first element of the cr_rights[] array contain total
number of elements in the array - 2. This means if those two bits are equal to
0, we have 2 array elements.

The top two bits in all remaining array elements should be 0.
The next five bits in all array elements contain array index. Only one bit is
used and bit position in this five-bits range defines array index. This means
there can be at most five array elements in the future.

To define new right the CAPRIGHT() macro must be used. The macro takes two
arguments - an array index and a bit to set, eg.

	#define	CAP_PDKILL	CAPRIGHT(1, 0x0000000000000800ULL)

We still support aliases that combine few rights, but the rights have to belong
to the same array element, eg:

	#define	CAP_LOOKUP	CAPRIGHT(0, 0x0000000000000400ULL)
	#define	CAP_FCHMOD	CAPRIGHT(0, 0x0000000000002000ULL)

	#define	CAP_FCHMODAT	(CAP_FCHMOD | CAP_LOOKUP)

There is new API to manage the new cap_rights_t structure:

	cap_rights_t *cap_rights_init(cap_rights_t *rights, ...);
	void cap_rights_set(cap_rights_t *rights, ...);
	void cap_rights_clear(cap_rights_t *rights, ...);
	bool cap_rights_is_set(const cap_rights_t *rights, ...);

	bool cap_rights_is_valid(const cap_rights_t *rights);
	void cap_rights_merge(cap_rights_t *dst, const cap_rights_t *src);
	void cap_rights_remove(cap_rights_t *dst, const cap_rights_t *src);
	bool cap_rights_contains(const cap_rights_t *big, const cap_rights_t *little);

Capability rights to the cap_rights_init(), cap_rights_set(),
cap_rights_clear() and cap_rights_is_set() functions are provided by
separating them with commas, eg:

	cap_rights_t rights;

	cap_rights_init(&rights, CAP_READ, CAP_WRITE, CAP_FSTAT);

There is no need to terminate the list of rights, as those functions are
actually macros that take care of the termination, eg:

	#define	cap_rights_set(rights, ...)				\
		__cap_rights_set((rights), __VA_ARGS__, 0ULL)
	void __cap_rights_set(cap_rights_t *rights, ...);

Thanks to using one bit as an array index we can assert in those functions that
there are no two rights belonging to different array elements provided
together. For example this is illegal and will be detected, because CAP_LOOKUP
belongs to element 0 and CAP_PDKILL to element 1:

	cap_rights_init(&rights, CAP_LOOKUP | CAP_PDKILL);

Providing several rights that belongs to the same array's element this way is
correct, but is not advised. It should only be used for aliases definition.

This commit also breaks compatibility with some existing Capsicum system calls,
but I see no other way to do that. This should be fine as Capsicum is still
experimental and this change is not going to 9.x.

Sponsored by:	The FreeBSD Foundation
2013-09-05 00:09:56 +00:00

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/*
* Copyright (c) 2007-2009 Google Inc. and Amit Singh
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
* OWNER 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.
*
* Copyright (C) 2005 Csaba Henk.
* All rights reserved.
*
* 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 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 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/module.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/capability.h>
#include <sys/conf.h>
#include <sys/filedesc.h>
#include <sys/uio.h>
#include <sys/malloc.h>
#include <sys/queue.h>
#include <sys/lock.h>
#include <sys/sx.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/namei.h>
#include <sys/mount.h>
#include <sys/sysctl.h>
#include <sys/fcntl.h>
#include "fuse.h"
#include "fuse_param.h"
#include "fuse_node.h"
#include "fuse_ipc.h"
#include "fuse_internal.h"
#include <sys/priv.h>
#include <security/mac/mac_framework.h>
#define FUSE_DEBUG_MODULE VFSOPS
#include "fuse_debug.h"
/* This will do for privilege types for now */
#ifndef PRIV_VFS_FUSE_ALLOWOTHER
#define PRIV_VFS_FUSE_ALLOWOTHER PRIV_VFS_MOUNT_NONUSER
#endif
#ifndef PRIV_VFS_FUSE_MOUNT_NONUSER
#define PRIV_VFS_FUSE_MOUNT_NONUSER PRIV_VFS_MOUNT_NONUSER
#endif
#ifndef PRIV_VFS_FUSE_SYNC_UNMOUNT
#define PRIV_VFS_FUSE_SYNC_UNMOUNT PRIV_VFS_MOUNT_NONUSER
#endif
static vfs_mount_t fuse_vfsop_mount;
static vfs_unmount_t fuse_vfsop_unmount;
static vfs_root_t fuse_vfsop_root;
static vfs_statfs_t fuse_vfsop_statfs;
struct vfsops fuse_vfsops = {
.vfs_mount = fuse_vfsop_mount,
.vfs_unmount = fuse_vfsop_unmount,
.vfs_root = fuse_vfsop_root,
.vfs_statfs = fuse_vfsop_statfs,
};
SYSCTL_INT(_vfs_fuse, OID_AUTO, init_backgrounded, CTLFLAG_RD,
0, 1, "indicate async handshake");
static int fuse_enforce_dev_perms = 0;
SYSCTL_LONG(_vfs_fuse, OID_AUTO, enforce_dev_perms, CTLFLAG_RW,
&fuse_enforce_dev_perms, 0,
"enforce fuse device permissions for secondary mounts");
static unsigned sync_unmount = 1;
SYSCTL_UINT(_vfs_fuse, OID_AUTO, sync_unmount, CTLFLAG_RW,
&sync_unmount, 0, "specify when to use synchronous unmount");
MALLOC_DEFINE(M_FUSEVFS, "fuse_filesystem", "buffer for fuse vfs layer");
static int
fuse_getdevice(const char *fspec, struct thread *td, struct cdev **fdevp)
{
struct nameidata nd, *ndp = &nd;
struct vnode *devvp;
struct cdev *fdev;
int err;
/*
* Not an update, or updating the name: look up the name
* and verify that it refers to a sensible disk device.
*/
NDINIT(ndp, LOOKUP, FOLLOW, UIO_SYSSPACE, fspec, td);
if ((err = namei(ndp)) != 0)
return err;
NDFREE(ndp, NDF_ONLY_PNBUF);
devvp = ndp->ni_vp;
if (devvp->v_type != VCHR) {
vrele(devvp);
return ENXIO;
}
fdev = devvp->v_rdev;
dev_ref(fdev);
if (fuse_enforce_dev_perms) {
/*
* Check if mounter can open the fuse device.
*
* This has significance only if we are doing a secondary mount
* which doesn't involve actually opening fuse devices, but we
* still want to enforce the permissions of the device (in
* order to keep control over the circle of fuse users).
*
* (In case of primary mounts, we are either the superuser so
* we can do anything anyway, or we can mount only if the
* device is already opened by us, ie. we are permitted to open
* the device.)
*/
#if 0
#ifdef MAC
err = mac_check_vnode_open(td->td_ucred, devvp, VREAD | VWRITE);
if (!err)
#endif
#endif /* 0 */
err = VOP_ACCESS(devvp, VREAD | VWRITE, td->td_ucred, td);
if (err) {
vrele(devvp);
dev_rel(fdev);
return err;
}
}
/*
* according to coda code, no extra lock is needed --
* although in sys/vnode.h this field is marked "v"
*/
vrele(devvp);
if (!fdev->si_devsw ||
strcmp("fuse", fdev->si_devsw->d_name)) {
dev_rel(fdev);
return ENXIO;
}
*fdevp = fdev;
return 0;
}
#define FUSE_FLAGOPT(fnam, fval) do { \
vfs_flagopt(opts, #fnam, &mntopts, fval); \
vfs_flagopt(opts, "__" #fnam, &__mntopts, fval); \
} while (0)
static int
fuse_vfsop_mount(struct mount *mp)
{
int err;
uint64_t mntopts, __mntopts;
int max_read_set;
uint32_t max_read;
int daemon_timeout;
int fd;
size_t len;
struct cdev *fdev;
struct fuse_data *data;
struct thread *td;
struct file *fp, *fptmp;
char *fspec, *subtype;
struct vfsoptlist *opts;
cap_rights_t rights;
subtype = NULL;
max_read_set = 0;
max_read = ~0;
err = 0;
mntopts = 0;
__mntopts = 0;
td = curthread;
fuse_trace_printf_vfsop();
if (mp->mnt_flag & MNT_UPDATE)
return EOPNOTSUPP;
MNT_ILOCK(mp);
mp->mnt_flag |= MNT_SYNCHRONOUS;
mp->mnt_data = NULL;
MNT_IUNLOCK(mp);
/* Get the new options passed to mount */
opts = mp->mnt_optnew;
if (!opts)
return EINVAL;
/* `fspath' contains the mount point (eg. /mnt/fuse/sshfs); REQUIRED */
if (!vfs_getopts(opts, "fspath", &err))
return err;
/* `from' contains the device name (eg. /dev/fuse0); REQUIRED */
fspec = vfs_getopts(opts, "from", &err);
if (!fspec)
return err;
/* `fd' contains the filedescriptor for this session; REQUIRED */
if (vfs_scanopt(opts, "fd", "%d", &fd) != 1)
return EINVAL;
err = fuse_getdevice(fspec, td, &fdev);
if (err != 0)
return err;
/*
* With the help of underscored options the mount program
* can inform us from the flags it sets by default
*/
FUSE_FLAGOPT(allow_other, FSESS_DAEMON_CAN_SPY);
FUSE_FLAGOPT(push_symlinks_in, FSESS_PUSH_SYMLINKS_IN);
FUSE_FLAGOPT(default_permissions, FSESS_DEFAULT_PERMISSIONS);
FUSE_FLAGOPT(no_attrcache, FSESS_NO_ATTRCACHE);
FUSE_FLAGOPT(no_readahed, FSESS_NO_READAHEAD);
FUSE_FLAGOPT(no_datacache, FSESS_NO_DATACACHE);
FUSE_FLAGOPT(no_namecache, FSESS_NO_NAMECACHE);
FUSE_FLAGOPT(no_mmap, FSESS_NO_MMAP);
FUSE_FLAGOPT(brokenio, FSESS_BROKENIO);
if (vfs_scanopt(opts, "max_read=", "%u", &max_read) == 1)
max_read_set = 1;
if (vfs_scanopt(opts, "timeout=", "%u", &daemon_timeout) == 1) {
if (daemon_timeout < FUSE_MIN_DAEMON_TIMEOUT)
daemon_timeout = FUSE_MIN_DAEMON_TIMEOUT;
else if (daemon_timeout > FUSE_MAX_DAEMON_TIMEOUT)
daemon_timeout = FUSE_MAX_DAEMON_TIMEOUT;
} else {
daemon_timeout = FUSE_DEFAULT_DAEMON_TIMEOUT;
}
subtype = vfs_getopts(opts, "subtype=", &err);
FS_DEBUG2G("mntopts 0x%jx\n", (uintmax_t)mntopts);
err = fget(td, fd, cap_rights_init(&rights, CAP_READ), &fp);
if (err != 0) {
FS_DEBUG("invalid or not opened device: data=%p\n", data);
goto out;
}
fptmp = td->td_fpop;
td->td_fpop = fp;
err = devfs_get_cdevpriv((void **)&data);
td->td_fpop = fptmp;
fdrop(fp, td);
FUSE_LOCK();
if (err != 0 || data == NULL || data->mp != NULL) {
FS_DEBUG("invalid or not opened device: data=%p data.mp=%p\n",
data, data != NULL ? data->mp : NULL);
err = ENXIO;
FUSE_UNLOCK();
goto out;
}
if (fdata_get_dead(data)) {
FS_DEBUG("device is dead during mount: data=%p\n", data);
err = ENOTCONN;
FUSE_UNLOCK();
goto out;
}
/* Sanity + permission checks */
if (!data->daemoncred)
panic("fuse daemon found, but identity unknown");
if (mntopts & FSESS_DAEMON_CAN_SPY)
err = priv_check(td, PRIV_VFS_FUSE_ALLOWOTHER);
if (err == 0 && td->td_ucred->cr_uid != data->daemoncred->cr_uid)
/* are we allowed to do the first mount? */
err = priv_check(td, PRIV_VFS_FUSE_MOUNT_NONUSER);
if (err) {
FUSE_UNLOCK();
goto out;
}
data->ref++;
data->mp = mp;
data->dataflags |= mntopts;
data->max_read = max_read;
data->daemon_timeout = daemon_timeout;
FUSE_UNLOCK();
vfs_getnewfsid(mp);
MNT_ILOCK(mp);
mp->mnt_data = data;
mp->mnt_flag |= MNT_LOCAL;
MNT_IUNLOCK(mp);
/* We need this here as this slot is used by getnewvnode() */
mp->mnt_stat.f_iosize = PAGE_SIZE;
if (subtype) {
strlcat(mp->mnt_stat.f_fstypename, ".", MFSNAMELEN);
strlcat(mp->mnt_stat.f_fstypename, subtype, MFSNAMELEN);
}
copystr(fspec, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, &len);
bzero(mp->mnt_stat.f_mntfromname + len, MNAMELEN - len);
FS_DEBUG2G("mp %p: %s\n", mp, mp->mnt_stat.f_mntfromname);
/* Now handshaking with daemon */
fuse_internal_send_init(data, td);
out:
if (err) {
FUSE_LOCK();
if (data->mp == mp) {
/*
* Destroy device only if we acquired reference to
* it
*/
FS_DEBUG("mount failed, destroy device: data=%p mp=%p"
" err=%d\n",
data, mp, err);
data->mp = NULL;
fdata_trydestroy(data);
}
FUSE_UNLOCK();
dev_rel(fdev);
}
return err;
}
static int
fuse_vfsop_unmount(struct mount *mp, int mntflags)
{
int err = 0;
int flags = 0;
struct cdev *fdev;
struct fuse_data *data;
struct fuse_dispatcher fdi;
struct thread *td = curthread;
fuse_trace_printf_vfsop();
if (mntflags & MNT_FORCE) {
flags |= FORCECLOSE;
}
data = fuse_get_mpdata(mp);
if (!data) {
panic("no private data for mount point?");
}
/* There is 1 extra root vnode reference (mp->mnt_data). */
FUSE_LOCK();
if (data->vroot != NULL) {
struct vnode *vroot = data->vroot;
data->vroot = NULL;
FUSE_UNLOCK();
vrele(vroot);
} else
FUSE_UNLOCK();
err = vflush(mp, 0, flags, td);
if (err) {
debug_printf("vflush failed");
return err;
}
if (fdata_get_dead(data)) {
goto alreadydead;
}
fdisp_init(&fdi, 0);
fdisp_make(&fdi, FUSE_DESTROY, mp, 0, td, NULL);
err = fdisp_wait_answ(&fdi);
fdisp_destroy(&fdi);
fdata_set_dead(data);
alreadydead:
FUSE_LOCK();
data->mp = NULL;
fdev = data->fdev;
fdata_trydestroy(data);
FUSE_UNLOCK();
MNT_ILOCK(mp);
mp->mnt_data = NULL;
mp->mnt_flag &= ~MNT_LOCAL;
MNT_IUNLOCK(mp);
dev_rel(fdev);
return 0;
}
static int
fuse_vfsop_root(struct mount *mp, int lkflags, struct vnode **vpp)
{
struct fuse_data *data = fuse_get_mpdata(mp);
int err = 0;
if (data->vroot != NULL) {
err = vget(data->vroot, lkflags, curthread);
if (err == 0)
*vpp = data->vroot;
} else {
err = fuse_vnode_get(mp, FUSE_ROOT_ID, NULL, vpp, NULL, VDIR);
if (err == 0) {
FUSE_LOCK();
MPASS(data->vroot == NULL || data->vroot == *vpp);
if (data->vroot == NULL) {
FS_DEBUG("new root vnode\n");
data->vroot = *vpp;
FUSE_UNLOCK();
vref(*vpp);
} else if (data->vroot != *vpp) {
FS_DEBUG("root vnode race\n");
FUSE_UNLOCK();
VOP_UNLOCK(*vpp, 0);
vrele(*vpp);
vrecycle(*vpp);
*vpp = data->vroot;
} else
FUSE_UNLOCK();
}
}
return err;
}
static int
fuse_vfsop_statfs(struct mount *mp, struct statfs *sbp)
{
struct fuse_dispatcher fdi;
int err = 0;
struct fuse_statfs_out *fsfo;
struct fuse_data *data;
FS_DEBUG2G("mp %p: %s\n", mp, mp->mnt_stat.f_mntfromname);
data = fuse_get_mpdata(mp);
if (!(data->dataflags & FSESS_INITED))
goto fake;
fdisp_init(&fdi, 0);
fdisp_make(&fdi, FUSE_STATFS, mp, FUSE_ROOT_ID, NULL, NULL);
err = fdisp_wait_answ(&fdi);
if (err) {
fdisp_destroy(&fdi);
if (err == ENOTCONN) {
/*
* We want to seem a legitimate fs even if the daemon
* is stiff dead... (so that, eg., we can still do path
* based unmounting after the daemon dies).
*/
goto fake;
}
return err;
}
fsfo = fdi.answ;
sbp->f_blocks = fsfo->st.blocks;
sbp->f_bfree = fsfo->st.bfree;
sbp->f_bavail = fsfo->st.bavail;
sbp->f_files = fsfo->st.files;
sbp->f_ffree = fsfo->st.ffree; /* cast from uint64_t to int64_t */
sbp->f_namemax = fsfo->st.namelen;
sbp->f_bsize = fsfo->st.frsize; /* cast from uint32_t to uint64_t */
FS_DEBUG("fuse_statfs_out -- blocks: %llu, bfree: %llu, bavail: %llu, "
"fil es: %llu, ffree: %llu, bsize: %i, namelen: %i\n",
(unsigned long long)fsfo->st.blocks,
(unsigned long long)fsfo->st.bfree,
(unsigned long long)fsfo->st.bavail,
(unsigned long long)fsfo->st.files,
(unsigned long long)fsfo->st.ffree, fsfo->st.bsize,
fsfo->st.namelen);
fdisp_destroy(&fdi);
return 0;
fake:
sbp->f_blocks = 0;
sbp->f_bfree = 0;
sbp->f_bavail = 0;
sbp->f_files = 0;
sbp->f_ffree = 0;
sbp->f_namemax = 0;
sbp->f_bsize = FUSE_DEFAULT_BLOCKSIZE;
return 0;
}
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