linux/fs/fuse/inode.c
Linus Torvalds 0cbee99269 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull user namespace updates from Eric Biederman:
 "Long ago and far away when user namespaces where young it was realized
  that allowing fresh mounts of proc and sysfs with only user namespace
  permissions could violate the basic rule that only root gets to decide
  if proc or sysfs should be mounted at all.

  Some hacks were put in place to reduce the worst of the damage could
  be done, and the common sense rule was adopted that fresh mounts of
  proc and sysfs should allow no more than bind mounts of proc and
  sysfs.  Unfortunately that rule has not been fully enforced.

  There are two kinds of gaps in that enforcement.  Only filesystems
  mounted on empty directories of proc and sysfs should be ignored but
  the test for empty directories was insufficient.  So in my tree
  directories on proc, sysctl and sysfs that will always be empty are
  created specially.  Every other technique is imperfect as an ordinary
  directory can have entries added even after a readdir returns and
  shows that the directory is empty.  Special creation of directories
  for mount points makes the code in the kernel a smidge clearer about
  it's purpose.  I asked container developers from the various container
  projects to help test this and no holes were found in the set of mount
  points on proc and sysfs that are created specially.

  This set of changes also starts enforcing the mount flags of fresh
  mounts of proc and sysfs are consistent with the existing mount of
  proc and sysfs.  I expected this to be the boring part of the work but
  unfortunately unprivileged userspace winds up mounting fresh copies of
  proc and sysfs with noexec and nosuid clear when root set those flags
  on the previous mount of proc and sysfs.  So for now only the atime,
  read-only and nodev attributes which userspace happens to keep
  consistent are enforced.  Dealing with the noexec and nosuid
  attributes remains for another time.

  This set of changes also addresses an issue with how open file
  descriptors from /proc/<pid>/ns/* are displayed.  Recently readlink of
  /proc/<pid>/fd has been triggering a WARN_ON that has not been
  meaningful since it was added (as all of the code in the kernel was
  converted) and is not now actively wrong.

  There is also a short list of issues that have not been fixed yet that
  I will mention briefly.

  It is possible to rename a directory from below to above a bind mount.
  At which point any directory pointers below the renamed directory can
  be walked up to the root directory of the filesystem.  With user
  namespaces enabled a bind mount of the bind mount can be created
  allowing the user to pick a directory whose children they can rename
  to outside of the bind mount.  This is challenging to fix and doubly
  so because all obvious solutions must touch code that is in the
  performance part of pathname resolution.

  As mentioned above there is also a question of how to ensure that
  developers by accident or with purpose do not introduce exectuable
  files on sysfs and proc and in doing so introduce security regressions
  in the current userspace that will not be immediately obvious and as
  such are likely to require breaking userspace in painful ways once
  they are recognized"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  vfs: Remove incorrect debugging WARN in prepend_path
  mnt: Update fs_fully_visible to test for permanently empty directories
  sysfs: Create mountpoints with sysfs_create_mount_point
  sysfs: Add support for permanently empty directories to serve as mount points.
  kernfs: Add support for always empty directories.
  proc: Allow creating permanently empty directories that serve as mount points
  sysctl: Allow creating permanently empty directories that serve as mountpoints.
  fs: Add helper functions for permanently empty directories.
  vfs: Ignore unlocked mounts in fs_fully_visible
  mnt: Modify fs_fully_visible to deal with locked ro nodev and atime
  mnt: Refactor the logic for mounting sysfs and proc in a user namespace
2015-07-03 15:20:57 -07:00

1377 lines
31 KiB
C

/*
FUSE: Filesystem in Userspace
Copyright (C) 2001-2008 Miklos Szeredi <miklos@szeredi.hu>
This program can be distributed under the terms of the GNU GPL.
See the file COPYING.
*/
#include "fuse_i.h"
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/seq_file.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/parser.h>
#include <linux/statfs.h>
#include <linux/random.h>
#include <linux/sched.h>
#include <linux/exportfs.h>
MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
MODULE_DESCRIPTION("Filesystem in Userspace");
MODULE_LICENSE("GPL");
static struct kmem_cache *fuse_inode_cachep;
struct list_head fuse_conn_list;
DEFINE_MUTEX(fuse_mutex);
static int set_global_limit(const char *val, struct kernel_param *kp);
unsigned max_user_bgreq;
module_param_call(max_user_bgreq, set_global_limit, param_get_uint,
&max_user_bgreq, 0644);
__MODULE_PARM_TYPE(max_user_bgreq, "uint");
MODULE_PARM_DESC(max_user_bgreq,
"Global limit for the maximum number of backgrounded requests an "
"unprivileged user can set");
unsigned max_user_congthresh;
module_param_call(max_user_congthresh, set_global_limit, param_get_uint,
&max_user_congthresh, 0644);
__MODULE_PARM_TYPE(max_user_congthresh, "uint");
MODULE_PARM_DESC(max_user_congthresh,
"Global limit for the maximum congestion threshold an "
"unprivileged user can set");
#define FUSE_SUPER_MAGIC 0x65735546
#define FUSE_DEFAULT_BLKSIZE 512
/** Maximum number of outstanding background requests */
#define FUSE_DEFAULT_MAX_BACKGROUND 12
/** Congestion starts at 75% of maximum */
#define FUSE_DEFAULT_CONGESTION_THRESHOLD (FUSE_DEFAULT_MAX_BACKGROUND * 3 / 4)
struct fuse_mount_data {
int fd;
unsigned rootmode;
kuid_t user_id;
kgid_t group_id;
unsigned fd_present:1;
unsigned rootmode_present:1;
unsigned user_id_present:1;
unsigned group_id_present:1;
unsigned flags;
unsigned max_read;
unsigned blksize;
};
struct fuse_forget_link *fuse_alloc_forget(void)
{
return kzalloc(sizeof(struct fuse_forget_link), GFP_KERNEL);
}
static struct inode *fuse_alloc_inode(struct super_block *sb)
{
struct inode *inode;
struct fuse_inode *fi;
inode = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);
if (!inode)
return NULL;
fi = get_fuse_inode(inode);
fi->i_time = 0;
fi->nodeid = 0;
fi->nlookup = 0;
fi->attr_version = 0;
fi->writectr = 0;
fi->orig_ino = 0;
fi->state = 0;
INIT_LIST_HEAD(&fi->write_files);
INIT_LIST_HEAD(&fi->queued_writes);
INIT_LIST_HEAD(&fi->writepages);
init_waitqueue_head(&fi->page_waitq);
fi->forget = fuse_alloc_forget();
if (!fi->forget) {
kmem_cache_free(fuse_inode_cachep, inode);
return NULL;
}
return inode;
}
static void fuse_i_callback(struct rcu_head *head)
{
struct inode *inode = container_of(head, struct inode, i_rcu);
kmem_cache_free(fuse_inode_cachep, inode);
}
static void fuse_destroy_inode(struct inode *inode)
{
struct fuse_inode *fi = get_fuse_inode(inode);
BUG_ON(!list_empty(&fi->write_files));
BUG_ON(!list_empty(&fi->queued_writes));
kfree(fi->forget);
call_rcu(&inode->i_rcu, fuse_i_callback);
}
static void fuse_evict_inode(struct inode *inode)
{
truncate_inode_pages_final(&inode->i_data);
clear_inode(inode);
if (inode->i_sb->s_flags & MS_ACTIVE) {
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_inode *fi = get_fuse_inode(inode);
fuse_queue_forget(fc, fi->forget, fi->nodeid, fi->nlookup);
fi->forget = NULL;
}
}
static int fuse_remount_fs(struct super_block *sb, int *flags, char *data)
{
sync_filesystem(sb);
if (*flags & MS_MANDLOCK)
return -EINVAL;
return 0;
}
/*
* ino_t is 32-bits on 32-bit arch. We have to squash the 64-bit value down
* so that it will fit.
*/
static ino_t fuse_squash_ino(u64 ino64)
{
ino_t ino = (ino_t) ino64;
if (sizeof(ino_t) < sizeof(u64))
ino ^= ino64 >> (sizeof(u64) - sizeof(ino_t)) * 8;
return ino;
}
void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
u64 attr_valid)
{
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_inode *fi = get_fuse_inode(inode);
fi->attr_version = ++fc->attr_version;
fi->i_time = attr_valid;
inode->i_ino = fuse_squash_ino(attr->ino);
inode->i_mode = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
set_nlink(inode, attr->nlink);
inode->i_uid = make_kuid(&init_user_ns, attr->uid);
inode->i_gid = make_kgid(&init_user_ns, attr->gid);
inode->i_blocks = attr->blocks;
inode->i_atime.tv_sec = attr->atime;
inode->i_atime.tv_nsec = attr->atimensec;
/* mtime from server may be stale due to local buffered write */
if (!fc->writeback_cache || !S_ISREG(inode->i_mode)) {
inode->i_mtime.tv_sec = attr->mtime;
inode->i_mtime.tv_nsec = attr->mtimensec;
inode->i_ctime.tv_sec = attr->ctime;
inode->i_ctime.tv_nsec = attr->ctimensec;
}
if (attr->blksize != 0)
inode->i_blkbits = ilog2(attr->blksize);
else
inode->i_blkbits = inode->i_sb->s_blocksize_bits;
/*
* Don't set the sticky bit in i_mode, unless we want the VFS
* to check permissions. This prevents failures due to the
* check in may_delete().
*/
fi->orig_i_mode = inode->i_mode;
if (!(fc->flags & FUSE_DEFAULT_PERMISSIONS))
inode->i_mode &= ~S_ISVTX;
fi->orig_ino = attr->ino;
}
void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
u64 attr_valid, u64 attr_version)
{
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_inode *fi = get_fuse_inode(inode);
bool is_wb = fc->writeback_cache;
loff_t oldsize;
struct timespec old_mtime;
spin_lock(&fc->lock);
if ((attr_version != 0 && fi->attr_version > attr_version) ||
test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {
spin_unlock(&fc->lock);
return;
}
old_mtime = inode->i_mtime;
fuse_change_attributes_common(inode, attr, attr_valid);
oldsize = inode->i_size;
/*
* In case of writeback_cache enabled, the cached writes beyond EOF
* extend local i_size without keeping userspace server in sync. So,
* attr->size coming from server can be stale. We cannot trust it.
*/
if (!is_wb || !S_ISREG(inode->i_mode))
i_size_write(inode, attr->size);
spin_unlock(&fc->lock);
if (!is_wb && S_ISREG(inode->i_mode)) {
bool inval = false;
if (oldsize != attr->size) {
truncate_pagecache(inode, attr->size);
inval = true;
} else if (fc->auto_inval_data) {
struct timespec new_mtime = {
.tv_sec = attr->mtime,
.tv_nsec = attr->mtimensec,
};
/*
* Auto inval mode also checks and invalidates if mtime
* has changed.
*/
if (!timespec_equal(&old_mtime, &new_mtime))
inval = true;
}
if (inval)
invalidate_inode_pages2(inode->i_mapping);
}
}
static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
{
inode->i_mode = attr->mode & S_IFMT;
inode->i_size = attr->size;
inode->i_mtime.tv_sec = attr->mtime;
inode->i_mtime.tv_nsec = attr->mtimensec;
inode->i_ctime.tv_sec = attr->ctime;
inode->i_ctime.tv_nsec = attr->ctimensec;
if (S_ISREG(inode->i_mode)) {
fuse_init_common(inode);
fuse_init_file_inode(inode);
} else if (S_ISDIR(inode->i_mode))
fuse_init_dir(inode);
else if (S_ISLNK(inode->i_mode))
fuse_init_symlink(inode);
else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
fuse_init_common(inode);
init_special_inode(inode, inode->i_mode,
new_decode_dev(attr->rdev));
} else
BUG();
}
int fuse_inode_eq(struct inode *inode, void *_nodeidp)
{
u64 nodeid = *(u64 *) _nodeidp;
if (get_node_id(inode) == nodeid)
return 1;
else
return 0;
}
static int fuse_inode_set(struct inode *inode, void *_nodeidp)
{
u64 nodeid = *(u64 *) _nodeidp;
get_fuse_inode(inode)->nodeid = nodeid;
return 0;
}
struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
int generation, struct fuse_attr *attr,
u64 attr_valid, u64 attr_version)
{
struct inode *inode;
struct fuse_inode *fi;
struct fuse_conn *fc = get_fuse_conn_super(sb);
retry:
inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
if (!inode)
return NULL;
if ((inode->i_state & I_NEW)) {
inode->i_flags |= S_NOATIME;
if (!fc->writeback_cache || !S_ISREG(attr->mode))
inode->i_flags |= S_NOCMTIME;
inode->i_generation = generation;
fuse_init_inode(inode, attr);
unlock_new_inode(inode);
} else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
/* Inode has changed type, any I/O on the old should fail */
make_bad_inode(inode);
iput(inode);
goto retry;
}
fi = get_fuse_inode(inode);
spin_lock(&fc->lock);
fi->nlookup++;
spin_unlock(&fc->lock);
fuse_change_attributes(inode, attr, attr_valid, attr_version);
return inode;
}
int fuse_reverse_inval_inode(struct super_block *sb, u64 nodeid,
loff_t offset, loff_t len)
{
struct inode *inode;
pgoff_t pg_start;
pgoff_t pg_end;
inode = ilookup5(sb, nodeid, fuse_inode_eq, &nodeid);
if (!inode)
return -ENOENT;
fuse_invalidate_attr(inode);
if (offset >= 0) {
pg_start = offset >> PAGE_CACHE_SHIFT;
if (len <= 0)
pg_end = -1;
else
pg_end = (offset + len - 1) >> PAGE_CACHE_SHIFT;
invalidate_inode_pages2_range(inode->i_mapping,
pg_start, pg_end);
}
iput(inode);
return 0;
}
static void fuse_umount_begin(struct super_block *sb)
{
fuse_abort_conn(get_fuse_conn_super(sb));
}
static void fuse_send_destroy(struct fuse_conn *fc)
{
struct fuse_req *req = fc->destroy_req;
if (req && fc->conn_init) {
fc->destroy_req = NULL;
req->in.h.opcode = FUSE_DESTROY;
__set_bit(FR_FORCE, &req->flags);
__clear_bit(FR_BACKGROUND, &req->flags);
fuse_request_send(fc, req);
fuse_put_request(fc, req);
}
}
static void fuse_bdi_destroy(struct fuse_conn *fc)
{
if (fc->bdi_initialized)
bdi_destroy(&fc->bdi);
}
static void fuse_put_super(struct super_block *sb)
{
struct fuse_conn *fc = get_fuse_conn_super(sb);
fuse_send_destroy(fc);
fuse_abort_conn(fc);
mutex_lock(&fuse_mutex);
list_del(&fc->entry);
fuse_ctl_remove_conn(fc);
mutex_unlock(&fuse_mutex);
fuse_bdi_destroy(fc);
fuse_conn_put(fc);
}
static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
{
stbuf->f_type = FUSE_SUPER_MAGIC;
stbuf->f_bsize = attr->bsize;
stbuf->f_frsize = attr->frsize;
stbuf->f_blocks = attr->blocks;
stbuf->f_bfree = attr->bfree;
stbuf->f_bavail = attr->bavail;
stbuf->f_files = attr->files;
stbuf->f_ffree = attr->ffree;
stbuf->f_namelen = attr->namelen;
/* fsid is left zero */
}
static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
{
struct super_block *sb = dentry->d_sb;
struct fuse_conn *fc = get_fuse_conn_super(sb);
FUSE_ARGS(args);
struct fuse_statfs_out outarg;
int err;
if (!fuse_allow_current_process(fc)) {
buf->f_type = FUSE_SUPER_MAGIC;
return 0;
}
memset(&outarg, 0, sizeof(outarg));
args.in.numargs = 0;
args.in.h.opcode = FUSE_STATFS;
args.in.h.nodeid = get_node_id(d_inode(dentry));
args.out.numargs = 1;
args.out.args[0].size = sizeof(outarg);
args.out.args[0].value = &outarg;
err = fuse_simple_request(fc, &args);
if (!err)
convert_fuse_statfs(buf, &outarg.st);
return err;
}
enum {
OPT_FD,
OPT_ROOTMODE,
OPT_USER_ID,
OPT_GROUP_ID,
OPT_DEFAULT_PERMISSIONS,
OPT_ALLOW_OTHER,
OPT_MAX_READ,
OPT_BLKSIZE,
OPT_ERR
};
static const match_table_t tokens = {
{OPT_FD, "fd=%u"},
{OPT_ROOTMODE, "rootmode=%o"},
{OPT_USER_ID, "user_id=%u"},
{OPT_GROUP_ID, "group_id=%u"},
{OPT_DEFAULT_PERMISSIONS, "default_permissions"},
{OPT_ALLOW_OTHER, "allow_other"},
{OPT_MAX_READ, "max_read=%u"},
{OPT_BLKSIZE, "blksize=%u"},
{OPT_ERR, NULL}
};
static int fuse_match_uint(substring_t *s, unsigned int *res)
{
int err = -ENOMEM;
char *buf = match_strdup(s);
if (buf) {
err = kstrtouint(buf, 10, res);
kfree(buf);
}
return err;
}
static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev)
{
char *p;
memset(d, 0, sizeof(struct fuse_mount_data));
d->max_read = ~0;
d->blksize = FUSE_DEFAULT_BLKSIZE;
while ((p = strsep(&opt, ",")) != NULL) {
int token;
int value;
unsigned uv;
substring_t args[MAX_OPT_ARGS];
if (!*p)
continue;
token = match_token(p, tokens, args);
switch (token) {
case OPT_FD:
if (match_int(&args[0], &value))
return 0;
d->fd = value;
d->fd_present = 1;
break;
case OPT_ROOTMODE:
if (match_octal(&args[0], &value))
return 0;
if (!fuse_valid_type(value))
return 0;
d->rootmode = value;
d->rootmode_present = 1;
break;
case OPT_USER_ID:
if (fuse_match_uint(&args[0], &uv))
return 0;
d->user_id = make_kuid(current_user_ns(), uv);
if (!uid_valid(d->user_id))
return 0;
d->user_id_present = 1;
break;
case OPT_GROUP_ID:
if (fuse_match_uint(&args[0], &uv))
return 0;
d->group_id = make_kgid(current_user_ns(), uv);
if (!gid_valid(d->group_id))
return 0;
d->group_id_present = 1;
break;
case OPT_DEFAULT_PERMISSIONS:
d->flags |= FUSE_DEFAULT_PERMISSIONS;
break;
case OPT_ALLOW_OTHER:
d->flags |= FUSE_ALLOW_OTHER;
break;
case OPT_MAX_READ:
if (match_int(&args[0], &value))
return 0;
d->max_read = value;
break;
case OPT_BLKSIZE:
if (!is_bdev || match_int(&args[0], &value))
return 0;
d->blksize = value;
break;
default:
return 0;
}
}
if (!d->fd_present || !d->rootmode_present ||
!d->user_id_present || !d->group_id_present)
return 0;
return 1;
}
static int fuse_show_options(struct seq_file *m, struct dentry *root)
{
struct super_block *sb = root->d_sb;
struct fuse_conn *fc = get_fuse_conn_super(sb);
seq_printf(m, ",user_id=%u", from_kuid_munged(&init_user_ns, fc->user_id));
seq_printf(m, ",group_id=%u", from_kgid_munged(&init_user_ns, fc->group_id));
if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
seq_puts(m, ",default_permissions");
if (fc->flags & FUSE_ALLOW_OTHER)
seq_puts(m, ",allow_other");
if (fc->max_read != ~0)
seq_printf(m, ",max_read=%u", fc->max_read);
if (sb->s_bdev && sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
seq_printf(m, ",blksize=%lu", sb->s_blocksize);
return 0;
}
static void fuse_iqueue_init(struct fuse_iqueue *fiq)
{
memset(fiq, 0, sizeof(struct fuse_iqueue));
init_waitqueue_head(&fiq->waitq);
INIT_LIST_HEAD(&fiq->pending);
INIT_LIST_HEAD(&fiq->interrupts);
fiq->forget_list_tail = &fiq->forget_list_head;
fiq->connected = 1;
}
static void fuse_pqueue_init(struct fuse_pqueue *fpq)
{
memset(fpq, 0, sizeof(struct fuse_pqueue));
spin_lock_init(&fpq->lock);
INIT_LIST_HEAD(&fpq->processing);
INIT_LIST_HEAD(&fpq->io);
fpq->connected = 1;
}
void fuse_conn_init(struct fuse_conn *fc)
{
memset(fc, 0, sizeof(*fc));
spin_lock_init(&fc->lock);
init_rwsem(&fc->killsb);
atomic_set(&fc->count, 1);
atomic_set(&fc->dev_count, 1);
init_waitqueue_head(&fc->blocked_waitq);
init_waitqueue_head(&fc->reserved_req_waitq);
fuse_iqueue_init(&fc->iq);
INIT_LIST_HEAD(&fc->bg_queue);
INIT_LIST_HEAD(&fc->entry);
INIT_LIST_HEAD(&fc->devices);
atomic_set(&fc->num_waiting, 0);
fc->max_background = FUSE_DEFAULT_MAX_BACKGROUND;
fc->congestion_threshold = FUSE_DEFAULT_CONGESTION_THRESHOLD;
fc->khctr = 0;
fc->polled_files = RB_ROOT;
fc->blocked = 0;
fc->initialized = 0;
fc->connected = 1;
fc->attr_version = 1;
get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
}
EXPORT_SYMBOL_GPL(fuse_conn_init);
void fuse_conn_put(struct fuse_conn *fc)
{
if (atomic_dec_and_test(&fc->count)) {
if (fc->destroy_req)
fuse_request_free(fc->destroy_req);
fc->release(fc);
}
}
EXPORT_SYMBOL_GPL(fuse_conn_put);
struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)
{
atomic_inc(&fc->count);
return fc;
}
EXPORT_SYMBOL_GPL(fuse_conn_get);
static struct inode *fuse_get_root_inode(struct super_block *sb, unsigned mode)
{
struct fuse_attr attr;
memset(&attr, 0, sizeof(attr));
attr.mode = mode;
attr.ino = FUSE_ROOT_ID;
attr.nlink = 1;
return fuse_iget(sb, 1, 0, &attr, 0, 0);
}
struct fuse_inode_handle {
u64 nodeid;
u32 generation;
};
static struct dentry *fuse_get_dentry(struct super_block *sb,
struct fuse_inode_handle *handle)
{
struct fuse_conn *fc = get_fuse_conn_super(sb);
struct inode *inode;
struct dentry *entry;
int err = -ESTALE;
if (handle->nodeid == 0)
goto out_err;
inode = ilookup5(sb, handle->nodeid, fuse_inode_eq, &handle->nodeid);
if (!inode) {
struct fuse_entry_out outarg;
struct qstr name;
if (!fc->export_support)
goto out_err;
name.len = 1;
name.name = ".";
err = fuse_lookup_name(sb, handle->nodeid, &name, &outarg,
&inode);
if (err && err != -ENOENT)
goto out_err;
if (err || !inode) {
err = -ESTALE;
goto out_err;
}
err = -EIO;
if (get_node_id(inode) != handle->nodeid)
goto out_iput;
}
err = -ESTALE;
if (inode->i_generation != handle->generation)
goto out_iput;
entry = d_obtain_alias(inode);
if (!IS_ERR(entry) && get_node_id(inode) != FUSE_ROOT_ID)
fuse_invalidate_entry_cache(entry);
return entry;
out_iput:
iput(inode);
out_err:
return ERR_PTR(err);
}
static int fuse_encode_fh(struct inode *inode, u32 *fh, int *max_len,
struct inode *parent)
{
int len = parent ? 6 : 3;
u64 nodeid;
u32 generation;
if (*max_len < len) {
*max_len = len;
return FILEID_INVALID;
}
nodeid = get_fuse_inode(inode)->nodeid;
generation = inode->i_generation;
fh[0] = (u32)(nodeid >> 32);
fh[1] = (u32)(nodeid & 0xffffffff);
fh[2] = generation;
if (parent) {
nodeid = get_fuse_inode(parent)->nodeid;
generation = parent->i_generation;
fh[3] = (u32)(nodeid >> 32);
fh[4] = (u32)(nodeid & 0xffffffff);
fh[5] = generation;
}
*max_len = len;
return parent ? 0x82 : 0x81;
}
static struct dentry *fuse_fh_to_dentry(struct super_block *sb,
struct fid *fid, int fh_len, int fh_type)
{
struct fuse_inode_handle handle;
if ((fh_type != 0x81 && fh_type != 0x82) || fh_len < 3)
return NULL;
handle.nodeid = (u64) fid->raw[0] << 32;
handle.nodeid |= (u64) fid->raw[1];
handle.generation = fid->raw[2];
return fuse_get_dentry(sb, &handle);
}
static struct dentry *fuse_fh_to_parent(struct super_block *sb,
struct fid *fid, int fh_len, int fh_type)
{
struct fuse_inode_handle parent;
if (fh_type != 0x82 || fh_len < 6)
return NULL;
parent.nodeid = (u64) fid->raw[3] << 32;
parent.nodeid |= (u64) fid->raw[4];
parent.generation = fid->raw[5];
return fuse_get_dentry(sb, &parent);
}
static struct dentry *fuse_get_parent(struct dentry *child)
{
struct inode *child_inode = d_inode(child);
struct fuse_conn *fc = get_fuse_conn(child_inode);
struct inode *inode;
struct dentry *parent;
struct fuse_entry_out outarg;
struct qstr name;
int err;
if (!fc->export_support)
return ERR_PTR(-ESTALE);
name.len = 2;
name.name = "..";
err = fuse_lookup_name(child_inode->i_sb, get_node_id(child_inode),
&name, &outarg, &inode);
if (err) {
if (err == -ENOENT)
return ERR_PTR(-ESTALE);
return ERR_PTR(err);
}
parent = d_obtain_alias(inode);
if (!IS_ERR(parent) && get_node_id(inode) != FUSE_ROOT_ID)
fuse_invalidate_entry_cache(parent);
return parent;
}
static const struct export_operations fuse_export_operations = {
.fh_to_dentry = fuse_fh_to_dentry,
.fh_to_parent = fuse_fh_to_parent,
.encode_fh = fuse_encode_fh,
.get_parent = fuse_get_parent,
};
static const struct super_operations fuse_super_operations = {
.alloc_inode = fuse_alloc_inode,
.destroy_inode = fuse_destroy_inode,
.evict_inode = fuse_evict_inode,
.write_inode = fuse_write_inode,
.drop_inode = generic_delete_inode,
.remount_fs = fuse_remount_fs,
.put_super = fuse_put_super,
.umount_begin = fuse_umount_begin,
.statfs = fuse_statfs,
.show_options = fuse_show_options,
};
static void sanitize_global_limit(unsigned *limit)
{
if (*limit == 0)
*limit = ((totalram_pages << PAGE_SHIFT) >> 13) /
sizeof(struct fuse_req);
if (*limit >= 1 << 16)
*limit = (1 << 16) - 1;
}
static int set_global_limit(const char *val, struct kernel_param *kp)
{
int rv;
rv = param_set_uint(val, kp);
if (rv)
return rv;
sanitize_global_limit((unsigned *)kp->arg);
return 0;
}
static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
{
int cap_sys_admin = capable(CAP_SYS_ADMIN);
if (arg->minor < 13)
return;
sanitize_global_limit(&max_user_bgreq);
sanitize_global_limit(&max_user_congthresh);
if (arg->max_background) {
fc->max_background = arg->max_background;
if (!cap_sys_admin && fc->max_background > max_user_bgreq)
fc->max_background = max_user_bgreq;
}
if (arg->congestion_threshold) {
fc->congestion_threshold = arg->congestion_threshold;
if (!cap_sys_admin &&
fc->congestion_threshold > max_user_congthresh)
fc->congestion_threshold = max_user_congthresh;
}
}
static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
{
struct fuse_init_out *arg = &req->misc.init_out;
if (req->out.h.error || arg->major != FUSE_KERNEL_VERSION)
fc->conn_error = 1;
else {
unsigned long ra_pages;
process_init_limits(fc, arg);
if (arg->minor >= 6) {
ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;
if (arg->flags & FUSE_ASYNC_READ)
fc->async_read = 1;
if (!(arg->flags & FUSE_POSIX_LOCKS))
fc->no_lock = 1;
if (arg->minor >= 17) {
if (!(arg->flags & FUSE_FLOCK_LOCKS))
fc->no_flock = 1;
} else {
if (!(arg->flags & FUSE_POSIX_LOCKS))
fc->no_flock = 1;
}
if (arg->flags & FUSE_ATOMIC_O_TRUNC)
fc->atomic_o_trunc = 1;
if (arg->minor >= 9) {
/* LOOKUP has dependency on proto version */
if (arg->flags & FUSE_EXPORT_SUPPORT)
fc->export_support = 1;
}
if (arg->flags & FUSE_BIG_WRITES)
fc->big_writes = 1;
if (arg->flags & FUSE_DONT_MASK)
fc->dont_mask = 1;
if (arg->flags & FUSE_AUTO_INVAL_DATA)
fc->auto_inval_data = 1;
if (arg->flags & FUSE_DO_READDIRPLUS) {
fc->do_readdirplus = 1;
if (arg->flags & FUSE_READDIRPLUS_AUTO)
fc->readdirplus_auto = 1;
}
if (arg->flags & FUSE_ASYNC_DIO)
fc->async_dio = 1;
if (arg->flags & FUSE_WRITEBACK_CACHE)
fc->writeback_cache = 1;
if (arg->time_gran && arg->time_gran <= 1000000000)
fc->sb->s_time_gran = arg->time_gran;
} else {
ra_pages = fc->max_read / PAGE_CACHE_SIZE;
fc->no_lock = 1;
fc->no_flock = 1;
}
fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);
fc->minor = arg->minor;
fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
fc->max_write = max_t(unsigned, 4096, fc->max_write);
fc->conn_init = 1;
}
fuse_set_initialized(fc);
wake_up_all(&fc->blocked_waitq);
}
static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
{
struct fuse_init_in *arg = &req->misc.init_in;
arg->major = FUSE_KERNEL_VERSION;
arg->minor = FUSE_KERNEL_MINOR_VERSION;
arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK |
FUSE_SPLICE_WRITE | FUSE_SPLICE_MOVE | FUSE_SPLICE_READ |
FUSE_FLOCK_LOCKS | FUSE_IOCTL_DIR | FUSE_AUTO_INVAL_DATA |
FUSE_DO_READDIRPLUS | FUSE_READDIRPLUS_AUTO | FUSE_ASYNC_DIO |
FUSE_WRITEBACK_CACHE | FUSE_NO_OPEN_SUPPORT;
req->in.h.opcode = FUSE_INIT;
req->in.numargs = 1;
req->in.args[0].size = sizeof(*arg);
req->in.args[0].value = arg;
req->out.numargs = 1;
/* Variable length argument used for backward compatibility
with interface version < 7.5. Rest of init_out is zeroed
by do_get_request(), so a short reply is not a problem */
req->out.argvar = 1;
req->out.args[0].size = sizeof(struct fuse_init_out);
req->out.args[0].value = &req->misc.init_out;
req->end = process_init_reply;
fuse_request_send_background(fc, req);
}
static void fuse_free_conn(struct fuse_conn *fc)
{
WARN_ON(!list_empty(&fc->devices));
kfree_rcu(fc, rcu);
}
static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)
{
int err;
fc->bdi.name = "fuse";
fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
/* fuse does it's own writeback accounting */
fc->bdi.capabilities = BDI_CAP_NO_ACCT_WB | BDI_CAP_STRICTLIMIT;
err = bdi_init(&fc->bdi);
if (err)
return err;
fc->bdi_initialized = 1;
if (sb->s_bdev) {
err = bdi_register(&fc->bdi, NULL, "%u:%u-fuseblk",
MAJOR(fc->dev), MINOR(fc->dev));
} else {
err = bdi_register_dev(&fc->bdi, fc->dev);
}
if (err)
return err;
/*
* For a single fuse filesystem use max 1% of dirty +
* writeback threshold.
*
* This gives about 1M of write buffer for memory maps on a
* machine with 1G and 10% dirty_ratio, which should be more
* than enough.
*
* Privileged users can raise it by writing to
*
* /sys/class/bdi/<bdi>/max_ratio
*/
bdi_set_max_ratio(&fc->bdi, 1);
return 0;
}
struct fuse_dev *fuse_dev_alloc(struct fuse_conn *fc)
{
struct fuse_dev *fud;
fud = kzalloc(sizeof(struct fuse_dev), GFP_KERNEL);
if (fud) {
fud->fc = fuse_conn_get(fc);
fuse_pqueue_init(&fud->pq);
spin_lock(&fc->lock);
list_add_tail(&fud->entry, &fc->devices);
spin_unlock(&fc->lock);
}
return fud;
}
EXPORT_SYMBOL_GPL(fuse_dev_alloc);
void fuse_dev_free(struct fuse_dev *fud)
{
struct fuse_conn *fc = fud->fc;
if (fc) {
spin_lock(&fc->lock);
list_del(&fud->entry);
spin_unlock(&fc->lock);
fuse_conn_put(fc);
}
kfree(fud);
}
EXPORT_SYMBOL_GPL(fuse_dev_free);
static int fuse_fill_super(struct super_block *sb, void *data, int silent)
{
struct fuse_dev *fud;
struct fuse_conn *fc;
struct inode *root;
struct fuse_mount_data d;
struct file *file;
struct dentry *root_dentry;
struct fuse_req *init_req;
int err;
int is_bdev = sb->s_bdev != NULL;
err = -EINVAL;
if (sb->s_flags & MS_MANDLOCK)
goto err;
sb->s_flags &= ~(MS_NOSEC | MS_I_VERSION);
if (!parse_fuse_opt(data, &d, is_bdev))
goto err;
if (is_bdev) {
#ifdef CONFIG_BLOCK
err = -EINVAL;
if (!sb_set_blocksize(sb, d.blksize))
goto err;
#endif
} else {
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
}
sb->s_magic = FUSE_SUPER_MAGIC;
sb->s_op = &fuse_super_operations;
sb->s_maxbytes = MAX_LFS_FILESIZE;
sb->s_time_gran = 1;
sb->s_export_op = &fuse_export_operations;
file = fget(d.fd);
err = -EINVAL;
if (!file)
goto err;
if ((file->f_op != &fuse_dev_operations) ||
(file->f_cred->user_ns != &init_user_ns))
goto err_fput;
fc = kmalloc(sizeof(*fc), GFP_KERNEL);
err = -ENOMEM;
if (!fc)
goto err_fput;
fuse_conn_init(fc);
fc->release = fuse_free_conn;
fud = fuse_dev_alloc(fc);
if (!fud)
goto err_put_conn;
fc->dev = sb->s_dev;
fc->sb = sb;
err = fuse_bdi_init(fc, sb);
if (err)
goto err_dev_free;
sb->s_bdi = &fc->bdi;
/* Handle umasking inside the fuse code */
if (sb->s_flags & MS_POSIXACL)
fc->dont_mask = 1;
sb->s_flags |= MS_POSIXACL;
fc->flags = d.flags;
fc->user_id = d.user_id;
fc->group_id = d.group_id;
fc->max_read = max_t(unsigned, 4096, d.max_read);
/* Used by get_root_inode() */
sb->s_fs_info = fc;
err = -ENOMEM;
root = fuse_get_root_inode(sb, d.rootmode);
root_dentry = d_make_root(root);
if (!root_dentry)
goto err_dev_free;
/* only now - we want root dentry with NULL ->d_op */
sb->s_d_op = &fuse_dentry_operations;
init_req = fuse_request_alloc(0);
if (!init_req)
goto err_put_root;
__set_bit(FR_BACKGROUND, &init_req->flags);
if (is_bdev) {
fc->destroy_req = fuse_request_alloc(0);
if (!fc->destroy_req)
goto err_free_init_req;
}
mutex_lock(&fuse_mutex);
err = -EINVAL;
if (file->private_data)
goto err_unlock;
err = fuse_ctl_add_conn(fc);
if (err)
goto err_unlock;
list_add_tail(&fc->entry, &fuse_conn_list);
sb->s_root = root_dentry;
file->private_data = fud;
mutex_unlock(&fuse_mutex);
/*
* atomic_dec_and_test() in fput() provides the necessary
* memory barrier for file->private_data to be visible on all
* CPUs after this
*/
fput(file);
fuse_send_init(fc, init_req);
return 0;
err_unlock:
mutex_unlock(&fuse_mutex);
err_free_init_req:
fuse_request_free(init_req);
err_put_root:
dput(root_dentry);
err_dev_free:
fuse_dev_free(fud);
err_put_conn:
fuse_bdi_destroy(fc);
fuse_conn_put(fc);
err_fput:
fput(file);
err:
return err;
}
static struct dentry *fuse_mount(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *raw_data)
{
return mount_nodev(fs_type, flags, raw_data, fuse_fill_super);
}
static void fuse_kill_sb_anon(struct super_block *sb)
{
struct fuse_conn *fc = get_fuse_conn_super(sb);
if (fc) {
down_write(&fc->killsb);
fc->sb = NULL;
up_write(&fc->killsb);
}
kill_anon_super(sb);
}
static struct file_system_type fuse_fs_type = {
.owner = THIS_MODULE,
.name = "fuse",
.fs_flags = FS_HAS_SUBTYPE,
.mount = fuse_mount,
.kill_sb = fuse_kill_sb_anon,
};
MODULE_ALIAS_FS("fuse");
#ifdef CONFIG_BLOCK
static struct dentry *fuse_mount_blk(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *raw_data)
{
return mount_bdev(fs_type, flags, dev_name, raw_data, fuse_fill_super);
}
static void fuse_kill_sb_blk(struct super_block *sb)
{
struct fuse_conn *fc = get_fuse_conn_super(sb);
if (fc) {
down_write(&fc->killsb);
fc->sb = NULL;
up_write(&fc->killsb);
}
kill_block_super(sb);
}
static struct file_system_type fuseblk_fs_type = {
.owner = THIS_MODULE,
.name = "fuseblk",
.mount = fuse_mount_blk,
.kill_sb = fuse_kill_sb_blk,
.fs_flags = FS_REQUIRES_DEV | FS_HAS_SUBTYPE,
};
MODULE_ALIAS_FS("fuseblk");
static inline int register_fuseblk(void)
{
return register_filesystem(&fuseblk_fs_type);
}
static inline void unregister_fuseblk(void)
{
unregister_filesystem(&fuseblk_fs_type);
}
#else
static inline int register_fuseblk(void)
{
return 0;
}
static inline void unregister_fuseblk(void)
{
}
#endif
static void fuse_inode_init_once(void *foo)
{
struct inode *inode = foo;
inode_init_once(inode);
}
static int __init fuse_fs_init(void)
{
int err;
fuse_inode_cachep = kmem_cache_create("fuse_inode",
sizeof(struct fuse_inode),
0, SLAB_HWCACHE_ALIGN,
fuse_inode_init_once);
err = -ENOMEM;
if (!fuse_inode_cachep)
goto out;
err = register_fuseblk();
if (err)
goto out2;
err = register_filesystem(&fuse_fs_type);
if (err)
goto out3;
return 0;
out3:
unregister_fuseblk();
out2:
kmem_cache_destroy(fuse_inode_cachep);
out:
return err;
}
static void fuse_fs_cleanup(void)
{
unregister_filesystem(&fuse_fs_type);
unregister_fuseblk();
/*
* Make sure all delayed rcu free inodes are flushed before we
* destroy cache.
*/
rcu_barrier();
kmem_cache_destroy(fuse_inode_cachep);
}
static struct kobject *fuse_kobj;
static int fuse_sysfs_init(void)
{
int err;
fuse_kobj = kobject_create_and_add("fuse", fs_kobj);
if (!fuse_kobj) {
err = -ENOMEM;
goto out_err;
}
err = sysfs_create_mount_point(fuse_kobj, "connections");
if (err)
goto out_fuse_unregister;
return 0;
out_fuse_unregister:
kobject_put(fuse_kobj);
out_err:
return err;
}
static void fuse_sysfs_cleanup(void)
{
sysfs_remove_mount_point(fuse_kobj, "connections");
kobject_put(fuse_kobj);
}
static int __init fuse_init(void)
{
int res;
printk(KERN_INFO "fuse init (API version %i.%i)\n",
FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
INIT_LIST_HEAD(&fuse_conn_list);
res = fuse_fs_init();
if (res)
goto err;
res = fuse_dev_init();
if (res)
goto err_fs_cleanup;
res = fuse_sysfs_init();
if (res)
goto err_dev_cleanup;
res = fuse_ctl_init();
if (res)
goto err_sysfs_cleanup;
sanitize_global_limit(&max_user_bgreq);
sanitize_global_limit(&max_user_congthresh);
return 0;
err_sysfs_cleanup:
fuse_sysfs_cleanup();
err_dev_cleanup:
fuse_dev_cleanup();
err_fs_cleanup:
fuse_fs_cleanup();
err:
return res;
}
static void __exit fuse_exit(void)
{
printk(KERN_DEBUG "fuse exit\n");
fuse_ctl_cleanup();
fuse_sysfs_cleanup();
fuse_fs_cleanup();
fuse_dev_cleanup();
}
module_init(fuse_init);
module_exit(fuse_exit);