linux/fs/fuse/ioctl.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2017 Red Hat, Inc.
*/
#include "fuse_i.h"
#include <linux/uio.h>
#include <linux/compat.h>
#include <linux/fileattr.h>
/*
* CUSE servers compiled on 32bit broke on 64bit kernels because the
* ABI was defined to be 'struct iovec' which is different on 32bit
* and 64bit. Fortunately we can determine which structure the server
* used from the size of the reply.
*/
static int fuse_copy_ioctl_iovec_old(struct iovec *dst, void *src,
size_t transferred, unsigned count,
bool is_compat)
{
#ifdef CONFIG_COMPAT
if (count * sizeof(struct compat_iovec) == transferred) {
struct compat_iovec *ciov = src;
unsigned i;
/*
* With this interface a 32bit server cannot support
* non-compat (i.e. ones coming from 64bit apps) ioctl
* requests
*/
if (!is_compat)
return -EINVAL;
for (i = 0; i < count; i++) {
dst[i].iov_base = compat_ptr(ciov[i].iov_base);
dst[i].iov_len = ciov[i].iov_len;
}
return 0;
}
#endif
if (count * sizeof(struct iovec) != transferred)
return -EIO;
memcpy(dst, src, transferred);
return 0;
}
/* Make sure iov_length() won't overflow */
static int fuse_verify_ioctl_iov(struct fuse_conn *fc, struct iovec *iov,
size_t count)
{
size_t n;
u32 max = fc->max_pages << PAGE_SHIFT;
for (n = 0; n < count; n++, iov++) {
if (iov->iov_len > (size_t) max)
return -ENOMEM;
max -= iov->iov_len;
}
return 0;
}
static int fuse_copy_ioctl_iovec(struct fuse_conn *fc, struct iovec *dst,
void *src, size_t transferred, unsigned count,
bool is_compat)
{
unsigned i;
struct fuse_ioctl_iovec *fiov = src;
if (fc->minor < 16) {
return fuse_copy_ioctl_iovec_old(dst, src, transferred,
count, is_compat);
}
if (count * sizeof(struct fuse_ioctl_iovec) != transferred)
return -EIO;
for (i = 0; i < count; i++) {
/* Did the server supply an inappropriate value? */
if (fiov[i].base != (unsigned long) fiov[i].base ||
fiov[i].len != (unsigned long) fiov[i].len)
return -EIO;
dst[i].iov_base = (void __user *) (unsigned long) fiov[i].base;
dst[i].iov_len = (size_t) fiov[i].len;
#ifdef CONFIG_COMPAT
if (is_compat &&
(ptr_to_compat(dst[i].iov_base) != fiov[i].base ||
(compat_size_t) dst[i].iov_len != fiov[i].len))
return -EIO;
#endif
}
return 0;
}
/*
* For ioctls, there is no generic way to determine how much memory
* needs to be read and/or written. Furthermore, ioctls are allowed
* to dereference the passed pointer, so the parameter requires deep
* copying but FUSE has no idea whatsoever about what to copy in or
* out.
*
* This is solved by allowing FUSE server to retry ioctl with
* necessary in/out iovecs. Let's assume the ioctl implementation
* needs to read in the following structure.
*
* struct a {
* char *buf;
* size_t buflen;
* }
*
* On the first callout to FUSE server, inarg->in_size and
* inarg->out_size will be NULL; then, the server completes the ioctl
* with FUSE_IOCTL_RETRY set in out->flags, out->in_iovs set to 1 and
* the actual iov array to
*
* { { .iov_base = inarg.arg, .iov_len = sizeof(struct a) } }
*
* which tells FUSE to copy in the requested area and retry the ioctl.
* On the second round, the server has access to the structure and
* from that it can tell what to look for next, so on the invocation,
* it sets FUSE_IOCTL_RETRY, out->in_iovs to 2 and iov array to
*
* { { .iov_base = inarg.arg, .iov_len = sizeof(struct a) },
* { .iov_base = a.buf, .iov_len = a.buflen } }
*
* FUSE will copy both struct a and the pointed buffer from the
* process doing the ioctl and retry ioctl with both struct a and the
* buffer.
*
* This time, FUSE server has everything it needs and completes ioctl
* without FUSE_IOCTL_RETRY which finishes the ioctl call.
*
* Copying data out works the same way.
*
* Note that if FUSE_IOCTL_UNRESTRICTED is clear, the kernel
* automatically initializes in and out iovs by decoding @cmd with
* _IOC_* macros and the server is not allowed to request RETRY. This
* limits ioctl data transfers to well-formed ioctls and is the forced
* behavior for all FUSE servers.
*/
long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
unsigned int flags)
{
struct fuse_file *ff = file->private_data;
struct fuse_mount *fm = ff->fm;
struct fuse_ioctl_in inarg = {
.fh = ff->fh,
.cmd = cmd,
.arg = arg,
.flags = flags
};
struct fuse_ioctl_out outarg;
struct iovec *iov_page = NULL;
struct iovec *in_iov = NULL, *out_iov = NULL;
unsigned int in_iovs = 0, out_iovs = 0, max_pages;
size_t in_size, out_size, c;
ssize_t transferred;
int err, i;
struct iov_iter ii;
struct fuse_args_pages ap = {};
#if BITS_PER_LONG == 32
inarg.flags |= FUSE_IOCTL_32BIT;
#else
if (flags & FUSE_IOCTL_COMPAT) {
inarg.flags |= FUSE_IOCTL_32BIT;
#ifdef CONFIG_X86_X32
if (in_x32_syscall())
inarg.flags |= FUSE_IOCTL_COMPAT_X32;
#endif
}
#endif
/* assume all the iovs returned by client always fits in a page */
BUILD_BUG_ON(sizeof(struct fuse_ioctl_iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);
err = -ENOMEM;
ap.pages = fuse_pages_alloc(fm->fc->max_pages, GFP_KERNEL, &ap.descs);
iov_page = (struct iovec *) __get_free_page(GFP_KERNEL);
if (!ap.pages || !iov_page)
goto out;
fuse_page_descs_length_init(ap.descs, 0, fm->fc->max_pages);
/*
* If restricted, initialize IO parameters as encoded in @cmd.
* RETRY from server is not allowed.
*/
if (!(flags & FUSE_IOCTL_UNRESTRICTED)) {
struct iovec *iov = iov_page;
iov->iov_base = (void __user *)arg;
iov->iov_len = _IOC_SIZE(cmd);
if (_IOC_DIR(cmd) & _IOC_WRITE) {
in_iov = iov;
in_iovs = 1;
}
if (_IOC_DIR(cmd) & _IOC_READ) {
out_iov = iov;
out_iovs = 1;
}
}
retry:
inarg.in_size = in_size = iov_length(in_iov, in_iovs);
inarg.out_size = out_size = iov_length(out_iov, out_iovs);
/*
* Out data can be used either for actual out data or iovs,
* make sure there always is at least one page.
*/
out_size = max_t(size_t, out_size, PAGE_SIZE);
max_pages = DIV_ROUND_UP(max(in_size, out_size), PAGE_SIZE);
/* make sure there are enough buffer pages and init request with them */
err = -ENOMEM;
if (max_pages > fm->fc->max_pages)
goto out;
while (ap.num_pages < max_pages) {
ap.pages[ap.num_pages] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
if (!ap.pages[ap.num_pages])
goto out;
ap.num_pages++;
}
/* okay, let's send it to the client */
ap.args.opcode = FUSE_IOCTL;
ap.args.nodeid = ff->nodeid;
ap.args.in_numargs = 1;
ap.args.in_args[0].size = sizeof(inarg);
ap.args.in_args[0].value = &inarg;
if (in_size) {
ap.args.in_numargs++;
ap.args.in_args[1].size = in_size;
ap.args.in_pages = true;
err = -EFAULT;
iov_iter_init(&ii, WRITE, in_iov, in_iovs, in_size);
for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
c = copy_page_from_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
if (c != PAGE_SIZE && iov_iter_count(&ii))
goto out;
}
}
ap.args.out_numargs = 2;
ap.args.out_args[0].size = sizeof(outarg);
ap.args.out_args[0].value = &outarg;
ap.args.out_args[1].size = out_size;
ap.args.out_pages = true;
ap.args.out_argvar = true;
transferred = fuse_simple_request(fm, &ap.args);
err = transferred;
if (transferred < 0)
goto out;
/* did it ask for retry? */
if (outarg.flags & FUSE_IOCTL_RETRY) {
void *vaddr;
/* no retry if in restricted mode */
err = -EIO;
if (!(flags & FUSE_IOCTL_UNRESTRICTED))
goto out;
in_iovs = outarg.in_iovs;
out_iovs = outarg.out_iovs;
/*
* Make sure things are in boundary, separate checks
* are to protect against overflow.
*/
err = -ENOMEM;
if (in_iovs > FUSE_IOCTL_MAX_IOV ||
out_iovs > FUSE_IOCTL_MAX_IOV ||
in_iovs + out_iovs > FUSE_IOCTL_MAX_IOV)
goto out;
vaddr = kmap_atomic(ap.pages[0]);
err = fuse_copy_ioctl_iovec(fm->fc, iov_page, vaddr,
transferred, in_iovs + out_iovs,
(flags & FUSE_IOCTL_COMPAT) != 0);
kunmap_atomic(vaddr);
if (err)
goto out;
in_iov = iov_page;
out_iov = in_iov + in_iovs;
err = fuse_verify_ioctl_iov(fm->fc, in_iov, in_iovs);
if (err)
goto out;
err = fuse_verify_ioctl_iov(fm->fc, out_iov, out_iovs);
if (err)
goto out;
goto retry;
}
err = -EIO;
if (transferred > inarg.out_size)
goto out;
err = -EFAULT;
iov_iter_init(&ii, READ, out_iov, out_iovs, transferred);
for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
c = copy_page_to_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
if (c != PAGE_SIZE && iov_iter_count(&ii))
goto out;
}
err = 0;
out:
free_page((unsigned long) iov_page);
while (ap.num_pages)
__free_page(ap.pages[--ap.num_pages]);
kfree(ap.pages);
return err ? err : outarg.result;
}
EXPORT_SYMBOL_GPL(fuse_do_ioctl);
long fuse_ioctl_common(struct file *file, unsigned int cmd,
unsigned long arg, unsigned int flags)
{
struct inode *inode = file_inode(file);
struct fuse_conn *fc = get_fuse_conn(inode);
if (!fuse_allow_current_process(fc))
return -EACCES;
if (fuse_is_bad(inode))
return -EIO;
return fuse_do_ioctl(file, cmd, arg, flags);
}
long fuse_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
return fuse_ioctl_common(file, cmd, arg, 0);
}
long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
return fuse_ioctl_common(file, cmd, arg, FUSE_IOCTL_COMPAT);
}
static int fuse_priv_ioctl(struct inode *inode, struct fuse_file *ff,
unsigned int cmd, void *ptr, size_t size)
{
struct fuse_mount *fm = ff->fm;
struct fuse_ioctl_in inarg;
struct fuse_ioctl_out outarg;
FUSE_ARGS(args);
int err;
memset(&inarg, 0, sizeof(inarg));
inarg.fh = ff->fh;
inarg.cmd = cmd;
#if BITS_PER_LONG == 32
inarg.flags |= FUSE_IOCTL_32BIT;
#endif
if (S_ISDIR(inode->i_mode))
inarg.flags |= FUSE_IOCTL_DIR;
if (_IOC_DIR(cmd) & _IOC_READ)
inarg.out_size = size;
if (_IOC_DIR(cmd) & _IOC_WRITE)
inarg.in_size = size;
args.opcode = FUSE_IOCTL;
args.nodeid = ff->nodeid;
args.in_numargs = 2;
args.in_args[0].size = sizeof(inarg);
args.in_args[0].value = &inarg;
args.in_args[1].size = inarg.in_size;
args.in_args[1].value = ptr;
args.out_numargs = 2;
args.out_args[0].size = sizeof(outarg);
args.out_args[0].value = &outarg;
args.out_args[1].size = inarg.out_size;
args.out_args[1].value = ptr;
err = fuse_simple_request(fm, &args);
if (!err && outarg.flags & FUSE_IOCTL_RETRY)
err = -EIO;
return err;
}
static struct fuse_file *fuse_priv_ioctl_prepare(struct inode *inode)
{
struct fuse_mount *fm = get_fuse_mount(inode);
bool isdir = S_ISDIR(inode->i_mode);
if (!S_ISREG(inode->i_mode) && !isdir)
return ERR_PTR(-ENOTTY);
return fuse_file_open(fm, get_node_id(inode), O_RDONLY, isdir);
}
static void fuse_priv_ioctl_cleanup(struct inode *inode, struct fuse_file *ff)
{
fuse_file_release(inode, ff, O_RDONLY, NULL, S_ISDIR(inode->i_mode));
}
int fuse_fileattr_get(struct dentry *dentry, struct fileattr *fa)
{
struct inode *inode = d_inode(dentry);
struct fuse_file *ff;
unsigned int flags;
struct fsxattr xfa;
int err;
ff = fuse_priv_ioctl_prepare(inode);
if (IS_ERR(ff))
return PTR_ERR(ff);
if (fa->flags_valid) {
err = fuse_priv_ioctl(inode, ff, FS_IOC_GETFLAGS,
&flags, sizeof(flags));
if (err)
goto cleanup;
fileattr_fill_flags(fa, flags);
} else {
err = fuse_priv_ioctl(inode, ff, FS_IOC_FSGETXATTR,
&xfa, sizeof(xfa));
if (err)
goto cleanup;
fileattr_fill_xflags(fa, xfa.fsx_xflags);
fa->fsx_extsize = xfa.fsx_extsize;
fa->fsx_nextents = xfa.fsx_nextents;
fa->fsx_projid = xfa.fsx_projid;
fa->fsx_cowextsize = xfa.fsx_cowextsize;
}
cleanup:
fuse_priv_ioctl_cleanup(inode, ff);
return err;
}
int fuse_fileattr_set(struct user_namespace *mnt_userns,
struct dentry *dentry, struct fileattr *fa)
{
struct inode *inode = d_inode(dentry);
struct fuse_file *ff;
unsigned int flags = fa->flags;
struct fsxattr xfa;
int err;
ff = fuse_priv_ioctl_prepare(inode);
if (IS_ERR(ff))
return PTR_ERR(ff);
if (fa->flags_valid) {
err = fuse_priv_ioctl(inode, ff, FS_IOC_SETFLAGS,
&flags, sizeof(flags));
if (err)
goto cleanup;
} else {
memset(&xfa, 0, sizeof(xfa));
xfa.fsx_xflags = fa->fsx_xflags;
xfa.fsx_extsize = fa->fsx_extsize;
xfa.fsx_nextents = fa->fsx_nextents;
xfa.fsx_projid = fa->fsx_projid;
xfa.fsx_cowextsize = fa->fsx_cowextsize;
err = fuse_priv_ioctl(inode, ff, FS_IOC_FSSETXATTR,
&xfa, sizeof(xfa));
}
cleanup:
fuse_priv_ioctl_cleanup(inode, ff);
return err;
}