kernel-ark/fs/fuse/file.c
Miklos Szeredi 9c8ef5614d [PATCH] fuse: scramble lock owner ID
VFS uses current->files pointer as lock owner ID, and it wouldn't be
prudent to expose this value to userspace.  So scramble it with XTEA using
a per connection random key, known only to the kernel.  Only one direction
needs to be implemented, since the ID is never sent in the reverse
direction.

The XTEA algorithm is implemented inline since it's simple enough to do so,
and this adds less complexity than if the crypto API were used.

Thanks to Jesper Juhl for the idea.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-25 10:01:20 -07:00

786 lines
18 KiB
C

/*
FUSE: Filesystem in Userspace
Copyright (C) 2001-2006 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/kernel.h>
static const struct file_operations fuse_direct_io_file_operations;
static int fuse_send_open(struct inode *inode, struct file *file, int isdir,
struct fuse_open_out *outargp)
{
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_open_in inarg;
struct fuse_req *req;
int err;
req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
memset(&inarg, 0, sizeof(inarg));
inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
req->in.h.opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
req->in.h.nodeid = get_node_id(inode);
req->in.numargs = 1;
req->in.args[0].size = sizeof(inarg);
req->in.args[0].value = &inarg;
req->out.numargs = 1;
req->out.args[0].size = sizeof(*outargp);
req->out.args[0].value = outargp;
request_send(fc, req);
err = req->out.h.error;
fuse_put_request(fc, req);
return err;
}
struct fuse_file *fuse_file_alloc(void)
{
struct fuse_file *ff;
ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL);
if (ff) {
ff->reserved_req = fuse_request_alloc();
if (!ff->reserved_req) {
kfree(ff);
ff = NULL;
}
}
return ff;
}
void fuse_file_free(struct fuse_file *ff)
{
fuse_request_free(ff->reserved_req);
kfree(ff);
}
void fuse_finish_open(struct inode *inode, struct file *file,
struct fuse_file *ff, struct fuse_open_out *outarg)
{
if (outarg->open_flags & FOPEN_DIRECT_IO)
file->f_op = &fuse_direct_io_file_operations;
if (!(outarg->open_flags & FOPEN_KEEP_CACHE))
invalidate_inode_pages(inode->i_mapping);
ff->fh = outarg->fh;
file->private_data = ff;
}
int fuse_open_common(struct inode *inode, struct file *file, int isdir)
{
struct fuse_open_out outarg;
struct fuse_file *ff;
int err;
/* VFS checks this, but only _after_ ->open() */
if (file->f_flags & O_DIRECT)
return -EINVAL;
err = generic_file_open(inode, file);
if (err)
return err;
/* If opening the root node, no lookup has been performed on
it, so the attributes must be refreshed */
if (get_node_id(inode) == FUSE_ROOT_ID) {
err = fuse_do_getattr(inode);
if (err)
return err;
}
ff = fuse_file_alloc();
if (!ff)
return -ENOMEM;
err = fuse_send_open(inode, file, isdir, &outarg);
if (err)
fuse_file_free(ff);
else {
if (isdir)
outarg.open_flags &= ~FOPEN_DIRECT_IO;
fuse_finish_open(inode, file, ff, &outarg);
}
return err;
}
struct fuse_req *fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags,
int opcode)
{
struct fuse_req *req = ff->reserved_req;
struct fuse_release_in *inarg = &req->misc.release_in;
inarg->fh = ff->fh;
inarg->flags = flags;
req->in.h.opcode = opcode;
req->in.h.nodeid = nodeid;
req->in.numargs = 1;
req->in.args[0].size = sizeof(struct fuse_release_in);
req->in.args[0].value = inarg;
kfree(ff);
return req;
}
int fuse_release_common(struct inode *inode, struct file *file, int isdir)
{
struct fuse_file *ff = file->private_data;
if (ff) {
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_req *req;
req = fuse_release_fill(ff, get_node_id(inode), file->f_flags,
isdir ? FUSE_RELEASEDIR : FUSE_RELEASE);
/* Hold vfsmount and dentry until release is finished */
req->vfsmount = mntget(file->f_vfsmnt);
req->dentry = dget(file->f_dentry);
request_send_background(fc, req);
}
/* Return value is ignored by VFS */
return 0;
}
static int fuse_open(struct inode *inode, struct file *file)
{
return fuse_open_common(inode, file, 0);
}
static int fuse_release(struct inode *inode, struct file *file)
{
return fuse_release_common(inode, file, 0);
}
/*
* Scramble the ID space with XTEA, so that the value of the files_struct
* pointer is not exposed to userspace.
*/
static u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id)
{
u32 *k = fc->scramble_key;
u64 v = (unsigned long) id;
u32 v0 = v;
u32 v1 = v >> 32;
u32 sum = 0;
int i;
for (i = 0; i < 32; i++) {
v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + k[sum & 3]);
sum += 0x9E3779B9;
v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + k[sum>>11 & 3]);
}
return (u64) v0 + ((u64) v1 << 32);
}
static int fuse_flush(struct file *file, fl_owner_t id)
{
struct inode *inode = file->f_dentry->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_file *ff = file->private_data;
struct fuse_req *req;
struct fuse_flush_in inarg;
int err;
if (is_bad_inode(inode))
return -EIO;
if (fc->no_flush)
return 0;
req = fuse_get_req_nofail(fc, file);
memset(&inarg, 0, sizeof(inarg));
inarg.fh = ff->fh;
inarg.lock_owner = fuse_lock_owner_id(fc, id);
req->in.h.opcode = FUSE_FLUSH;
req->in.h.nodeid = get_node_id(inode);
req->in.numargs = 1;
req->in.args[0].size = sizeof(inarg);
req->in.args[0].value = &inarg;
req->force = 1;
request_send(fc, req);
err = req->out.h.error;
fuse_put_request(fc, req);
if (err == -ENOSYS) {
fc->no_flush = 1;
err = 0;
}
return err;
}
int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
int isdir)
{
struct inode *inode = de->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_file *ff = file->private_data;
struct fuse_req *req;
struct fuse_fsync_in inarg;
int err;
if (is_bad_inode(inode))
return -EIO;
if ((!isdir && fc->no_fsync) || (isdir && fc->no_fsyncdir))
return 0;
req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
memset(&inarg, 0, sizeof(inarg));
inarg.fh = ff->fh;
inarg.fsync_flags = datasync ? 1 : 0;
req->in.h.opcode = isdir ? FUSE_FSYNCDIR : FUSE_FSYNC;
req->in.h.nodeid = get_node_id(inode);
req->in.numargs = 1;
req->in.args[0].size = sizeof(inarg);
req->in.args[0].value = &inarg;
request_send(fc, req);
err = req->out.h.error;
fuse_put_request(fc, req);
if (err == -ENOSYS) {
if (isdir)
fc->no_fsyncdir = 1;
else
fc->no_fsync = 1;
err = 0;
}
return err;
}
static int fuse_fsync(struct file *file, struct dentry *de, int datasync)
{
return fuse_fsync_common(file, de, datasync, 0);
}
void fuse_read_fill(struct fuse_req *req, struct file *file,
struct inode *inode, loff_t pos, size_t count, int opcode)
{
struct fuse_file *ff = file->private_data;
struct fuse_read_in *inarg = &req->misc.read_in;
inarg->fh = ff->fh;
inarg->offset = pos;
inarg->size = count;
req->in.h.opcode = opcode;
req->in.h.nodeid = get_node_id(inode);
req->in.numargs = 1;
req->in.args[0].size = sizeof(struct fuse_read_in);
req->in.args[0].value = inarg;
req->out.argpages = 1;
req->out.argvar = 1;
req->out.numargs = 1;
req->out.args[0].size = count;
}
static size_t fuse_send_read(struct fuse_req *req, struct file *file,
struct inode *inode, loff_t pos, size_t count)
{
struct fuse_conn *fc = get_fuse_conn(inode);
fuse_read_fill(req, file, inode, pos, count, FUSE_READ);
request_send(fc, req);
return req->out.args[0].size;
}
static int fuse_readpage(struct file *file, struct page *page)
{
struct inode *inode = page->mapping->host;
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_req *req;
int err;
err = -EIO;
if (is_bad_inode(inode))
goto out;
req = fuse_get_req(fc);
err = PTR_ERR(req);
if (IS_ERR(req))
goto out;
req->out.page_zeroing = 1;
req->num_pages = 1;
req->pages[0] = page;
fuse_send_read(req, file, inode, page_offset(page), PAGE_CACHE_SIZE);
err = req->out.h.error;
fuse_put_request(fc, req);
if (!err)
SetPageUptodate(page);
fuse_invalidate_attr(inode); /* atime changed */
out:
unlock_page(page);
return err;
}
static void fuse_readpages_end(struct fuse_conn *fc, struct fuse_req *req)
{
int i;
fuse_invalidate_attr(req->pages[0]->mapping->host); /* atime changed */
for (i = 0; i < req->num_pages; i++) {
struct page *page = req->pages[i];
if (!req->out.h.error)
SetPageUptodate(page);
else
SetPageError(page);
unlock_page(page);
}
fuse_put_request(fc, req);
}
static void fuse_send_readpages(struct fuse_req *req, struct file *file,
struct inode *inode)
{
struct fuse_conn *fc = get_fuse_conn(inode);
loff_t pos = page_offset(req->pages[0]);
size_t count = req->num_pages << PAGE_CACHE_SHIFT;
req->out.page_zeroing = 1;
fuse_read_fill(req, file, inode, pos, count, FUSE_READ);
if (fc->async_read) {
get_file(file);
req->file = file;
req->end = fuse_readpages_end;
request_send_background(fc, req);
} else {
request_send(fc, req);
fuse_readpages_end(fc, req);
}
}
struct fuse_readpages_data {
struct fuse_req *req;
struct file *file;
struct inode *inode;
};
static int fuse_readpages_fill(void *_data, struct page *page)
{
struct fuse_readpages_data *data = _data;
struct fuse_req *req = data->req;
struct inode *inode = data->inode;
struct fuse_conn *fc = get_fuse_conn(inode);
if (req->num_pages &&
(req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
(req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
req->pages[req->num_pages - 1]->index + 1 != page->index)) {
fuse_send_readpages(req, data->file, inode);
data->req = req = fuse_get_req(fc);
if (IS_ERR(req)) {
unlock_page(page);
return PTR_ERR(req);
}
}
req->pages[req->num_pages] = page;
req->num_pages ++;
return 0;
}
static int fuse_readpages(struct file *file, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages)
{
struct inode *inode = mapping->host;
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_readpages_data data;
int err;
if (is_bad_inode(inode))
return -EIO;
data.file = file;
data.inode = inode;
data.req = fuse_get_req(fc);
if (IS_ERR(data.req))
return PTR_ERR(data.req);
err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
if (!err) {
if (data.req->num_pages)
fuse_send_readpages(data.req, file, inode);
else
fuse_put_request(fc, data.req);
}
return err;
}
static size_t fuse_send_write(struct fuse_req *req, struct file *file,
struct inode *inode, loff_t pos, size_t count)
{
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_file *ff = file->private_data;
struct fuse_write_in inarg;
struct fuse_write_out outarg;
memset(&inarg, 0, sizeof(struct fuse_write_in));
inarg.fh = ff->fh;
inarg.offset = pos;
inarg.size = count;
req->in.h.opcode = FUSE_WRITE;
req->in.h.nodeid = get_node_id(inode);
req->in.argpages = 1;
req->in.numargs = 2;
req->in.args[0].size = sizeof(struct fuse_write_in);
req->in.args[0].value = &inarg;
req->in.args[1].size = count;
req->out.numargs = 1;
req->out.args[0].size = sizeof(struct fuse_write_out);
req->out.args[0].value = &outarg;
request_send(fc, req);
return outarg.size;
}
static int fuse_prepare_write(struct file *file, struct page *page,
unsigned offset, unsigned to)
{
/* No op */
return 0;
}
static int fuse_commit_write(struct file *file, struct page *page,
unsigned offset, unsigned to)
{
int err;
size_t nres;
unsigned count = to - offset;
struct inode *inode = page->mapping->host;
struct fuse_conn *fc = get_fuse_conn(inode);
loff_t pos = page_offset(page) + offset;
struct fuse_req *req;
if (is_bad_inode(inode))
return -EIO;
req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
req->num_pages = 1;
req->pages[0] = page;
req->page_offset = offset;
nres = fuse_send_write(req, file, inode, pos, count);
err = req->out.h.error;
fuse_put_request(fc, req);
if (!err && nres != count)
err = -EIO;
if (!err) {
pos += count;
if (pos > i_size_read(inode))
i_size_write(inode, pos);
if (offset == 0 && to == PAGE_CACHE_SIZE) {
clear_page_dirty(page);
SetPageUptodate(page);
}
}
fuse_invalidate_attr(inode);
return err;
}
static void fuse_release_user_pages(struct fuse_req *req, int write)
{
unsigned i;
for (i = 0; i < req->num_pages; i++) {
struct page *page = req->pages[i];
if (write)
set_page_dirty_lock(page);
put_page(page);
}
}
static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf,
unsigned nbytes, int write)
{
unsigned long user_addr = (unsigned long) buf;
unsigned offset = user_addr & ~PAGE_MASK;
int npages;
/* This doesn't work with nfsd */
if (!current->mm)
return -EPERM;
nbytes = min(nbytes, (unsigned) FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
npages = min(max(npages, 1), FUSE_MAX_PAGES_PER_REQ);
down_read(&current->mm->mmap_sem);
npages = get_user_pages(current, current->mm, user_addr, npages, write,
0, req->pages, NULL);
up_read(&current->mm->mmap_sem);
if (npages < 0)
return npages;
req->num_pages = npages;
req->page_offset = offset;
return 0;
}
static ssize_t fuse_direct_io(struct file *file, const char __user *buf,
size_t count, loff_t *ppos, int write)
{
struct inode *inode = file->f_dentry->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
size_t nmax = write ? fc->max_write : fc->max_read;
loff_t pos = *ppos;
ssize_t res = 0;
struct fuse_req *req;
if (is_bad_inode(inode))
return -EIO;
req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
while (count) {
size_t nres;
size_t nbytes = min(count, nmax);
int err = fuse_get_user_pages(req, buf, nbytes, !write);
if (err) {
res = err;
break;
}
nbytes = (req->num_pages << PAGE_SHIFT) - req->page_offset;
nbytes = min(count, nbytes);
if (write)
nres = fuse_send_write(req, file, inode, pos, nbytes);
else
nres = fuse_send_read(req, file, inode, pos, nbytes);
fuse_release_user_pages(req, !write);
if (req->out.h.error) {
if (!res)
res = req->out.h.error;
break;
} else if (nres > nbytes) {
res = -EIO;
break;
}
count -= nres;
res += nres;
pos += nres;
buf += nres;
if (nres != nbytes)
break;
if (count) {
fuse_put_request(fc, req);
req = fuse_get_req(fc);
if (IS_ERR(req))
break;
}
}
fuse_put_request(fc, req);
if (res > 0) {
if (write && pos > i_size_read(inode))
i_size_write(inode, pos);
*ppos = pos;
}
fuse_invalidate_attr(inode);
return res;
}
static ssize_t fuse_direct_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
return fuse_direct_io(file, buf, count, ppos, 0);
}
static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct inode *inode = file->f_dentry->d_inode;
ssize_t res;
/* Don't allow parallel writes to the same file */
mutex_lock(&inode->i_mutex);
res = fuse_direct_io(file, buf, count, ppos, 1);
mutex_unlock(&inode->i_mutex);
return res;
}
static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
{
if ((vma->vm_flags & VM_SHARED)) {
if ((vma->vm_flags & VM_WRITE))
return -ENODEV;
else
vma->vm_flags &= ~VM_MAYWRITE;
}
return generic_file_mmap(file, vma);
}
static int fuse_set_page_dirty(struct page *page)
{
printk("fuse_set_page_dirty: should not happen\n");
dump_stack();
return 0;
}
static int convert_fuse_file_lock(const struct fuse_file_lock *ffl,
struct file_lock *fl)
{
switch (ffl->type) {
case F_UNLCK:
break;
case F_RDLCK:
case F_WRLCK:
if (ffl->start > OFFSET_MAX || ffl->end > OFFSET_MAX ||
ffl->end < ffl->start)
return -EIO;
fl->fl_start = ffl->start;
fl->fl_end = ffl->end;
fl->fl_pid = ffl->pid;
break;
default:
return -EIO;
}
fl->fl_type = ffl->type;
return 0;
}
static void fuse_lk_fill(struct fuse_req *req, struct file *file,
const struct file_lock *fl, int opcode, pid_t pid)
{
struct inode *inode = file->f_dentry->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_file *ff = file->private_data;
struct fuse_lk_in *arg = &req->misc.lk_in;
arg->fh = ff->fh;
arg->owner = fuse_lock_owner_id(fc, fl->fl_owner);
arg->lk.start = fl->fl_start;
arg->lk.end = fl->fl_end;
arg->lk.type = fl->fl_type;
arg->lk.pid = pid;
req->in.h.opcode = opcode;
req->in.h.nodeid = get_node_id(inode);
req->in.numargs = 1;
req->in.args[0].size = sizeof(*arg);
req->in.args[0].value = arg;
}
static int fuse_getlk(struct file *file, struct file_lock *fl)
{
struct inode *inode = file->f_dentry->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_req *req;
struct fuse_lk_out outarg;
int err;
req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
fuse_lk_fill(req, file, fl, FUSE_GETLK, 0);
req->out.numargs = 1;
req->out.args[0].size = sizeof(outarg);
req->out.args[0].value = &outarg;
request_send(fc, req);
err = req->out.h.error;
fuse_put_request(fc, req);
if (!err)
err = convert_fuse_file_lock(&outarg.lk, fl);
return err;
}
static int fuse_setlk(struct file *file, struct file_lock *fl)
{
struct inode *inode = file->f_dentry->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_req *req;
int opcode = (fl->fl_flags & FL_SLEEP) ? FUSE_SETLKW : FUSE_SETLK;
pid_t pid = fl->fl_type != F_UNLCK ? current->tgid : 0;
int err;
/* Unlock on close is handled by the flush method */
if (fl->fl_flags & FL_CLOSE)
return 0;
req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
fuse_lk_fill(req, file, fl, opcode, pid);
request_send(fc, req);
err = req->out.h.error;
/* locking is restartable */
if (err == -EINTR)
err = -ERESTARTSYS;
fuse_put_request(fc, req);
return err;
}
static int fuse_file_lock(struct file *file, int cmd, struct file_lock *fl)
{
struct inode *inode = file->f_dentry->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
int err;
if (cmd == F_GETLK) {
if (fc->no_lock) {
if (!posix_test_lock(file, fl, fl))
fl->fl_type = F_UNLCK;
err = 0;
} else
err = fuse_getlk(file, fl);
} else {
if (fc->no_lock)
err = posix_lock_file_wait(file, fl);
else
err = fuse_setlk(file, fl);
}
return err;
}
static const struct file_operations fuse_file_operations = {
.llseek = generic_file_llseek,
.read = generic_file_read,
.write = generic_file_write,
.mmap = fuse_file_mmap,
.open = fuse_open,
.flush = fuse_flush,
.release = fuse_release,
.fsync = fuse_fsync,
.lock = fuse_file_lock,
.sendfile = generic_file_sendfile,
};
static const struct file_operations fuse_direct_io_file_operations = {
.llseek = generic_file_llseek,
.read = fuse_direct_read,
.write = fuse_direct_write,
.open = fuse_open,
.flush = fuse_flush,
.release = fuse_release,
.fsync = fuse_fsync,
.lock = fuse_file_lock,
/* no mmap and sendfile */
};
static struct address_space_operations fuse_file_aops = {
.readpage = fuse_readpage,
.prepare_write = fuse_prepare_write,
.commit_write = fuse_commit_write,
.readpages = fuse_readpages,
.set_page_dirty = fuse_set_page_dirty,
};
void fuse_init_file_inode(struct inode *inode)
{
inode->i_fop = &fuse_file_operations;
inode->i_data.a_ops = &fuse_file_aops;
}