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305 lines
7.5 KiB
305 lines
7.5 KiB
// SPDX-License-Identifier: GPL-2.0
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#include "fuse_i.h"
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#include <linux/file.h>
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#include <linux/fuse.h>
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#include <linux/idr.h>
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#include <linux/uio.h>
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#define PASSTHROUGH_IOCB_MASK \
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(IOCB_APPEND | IOCB_DSYNC | IOCB_HIPRI | IOCB_NOWAIT | IOCB_SYNC)
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struct fuse_aio_req {
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struct kiocb iocb;
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struct kiocb *iocb_fuse;
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};
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static inline void kiocb_clone(struct kiocb *kiocb, struct kiocb *kiocb_src,
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struct file *filp)
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{
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*kiocb = (struct kiocb){
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.ki_filp = filp,
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.ki_flags = kiocb_src->ki_flags,
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.ki_hint = kiocb_src->ki_hint,
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.ki_pos = kiocb_src->ki_pos,
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};
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}
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static void fuse_file_accessed(struct file *dst_file, struct file *src_file)
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{
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struct inode *dst_inode;
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struct inode *src_inode;
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if (dst_file->f_flags & O_NOATIME)
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return;
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dst_inode = file_inode(dst_file);
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src_inode = file_inode(src_file);
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if ((!timespec64_equal(&dst_inode->i_mtime, &src_inode->i_mtime) ||
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!timespec64_equal(&dst_inode->i_ctime, &src_inode->i_ctime))) {
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dst_inode->i_mtime = src_inode->i_mtime;
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dst_inode->i_ctime = src_inode->i_ctime;
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}
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touch_atime(&dst_file->f_path);
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}
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static void fuse_copyattr(struct file *dst_file, struct file *src_file)
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{
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struct inode *dst = file_inode(dst_file);
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struct inode *src = file_inode(src_file);
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dst->i_atime = src->i_atime;
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dst->i_mtime = src->i_mtime;
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dst->i_ctime = src->i_ctime;
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i_size_write(dst, i_size_read(src));
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}
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static void fuse_aio_cleanup_handler(struct fuse_aio_req *aio_req)
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{
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struct kiocb *iocb = &aio_req->iocb;
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struct kiocb *iocb_fuse = aio_req->iocb_fuse;
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if (iocb->ki_flags & IOCB_WRITE) {
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__sb_writers_acquired(file_inode(iocb->ki_filp)->i_sb,
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SB_FREEZE_WRITE);
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file_end_write(iocb->ki_filp);
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fuse_copyattr(iocb_fuse->ki_filp, iocb->ki_filp);
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}
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iocb_fuse->ki_pos = iocb->ki_pos;
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kfree(aio_req);
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}
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static void fuse_aio_rw_complete(struct kiocb *iocb, long res, long res2)
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{
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struct fuse_aio_req *aio_req =
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container_of(iocb, struct fuse_aio_req, iocb);
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struct kiocb *iocb_fuse = aio_req->iocb_fuse;
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fuse_aio_cleanup_handler(aio_req);
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iocb_fuse->ki_complete(iocb_fuse, res, res2);
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}
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ssize_t fuse_passthrough_read_iter(struct kiocb *iocb_fuse,
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struct iov_iter *iter)
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{
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ssize_t ret;
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const struct cred *old_cred;
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struct file *fuse_filp = iocb_fuse->ki_filp;
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struct fuse_file *ff = fuse_filp->private_data;
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struct file *passthrough_filp = ff->passthrough.filp;
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if (!iov_iter_count(iter))
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return 0;
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old_cred = override_creds(ff->passthrough.cred);
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if (is_sync_kiocb(iocb_fuse)) {
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ret = vfs_iter_read(passthrough_filp, iter, &iocb_fuse->ki_pos,
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iocb_to_rw_flags(iocb_fuse->ki_flags,
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PASSTHROUGH_IOCB_MASK));
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} else {
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struct fuse_aio_req *aio_req;
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aio_req = kmalloc(sizeof(struct fuse_aio_req), GFP_KERNEL);
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if (!aio_req) {
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ret = -ENOMEM;
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goto out;
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}
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aio_req->iocb_fuse = iocb_fuse;
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kiocb_clone(&aio_req->iocb, iocb_fuse, passthrough_filp);
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aio_req->iocb.ki_complete = fuse_aio_rw_complete;
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ret = call_read_iter(passthrough_filp, &aio_req->iocb, iter);
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if (ret != -EIOCBQUEUED)
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fuse_aio_cleanup_handler(aio_req);
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}
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out:
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revert_creds(old_cred);
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fuse_file_accessed(fuse_filp, passthrough_filp);
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return ret;
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}
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ssize_t fuse_passthrough_write_iter(struct kiocb *iocb_fuse,
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struct iov_iter *iter)
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{
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ssize_t ret;
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const struct cred *old_cred;
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struct file *fuse_filp = iocb_fuse->ki_filp;
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struct fuse_file *ff = fuse_filp->private_data;
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struct inode *fuse_inode = file_inode(fuse_filp);
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struct file *passthrough_filp = ff->passthrough.filp;
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struct inode *passthrough_inode = file_inode(passthrough_filp);
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if (!iov_iter_count(iter))
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return 0;
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inode_lock(fuse_inode);
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fuse_copyattr(fuse_filp, passthrough_filp);
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old_cred = override_creds(ff->passthrough.cred);
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if (is_sync_kiocb(iocb_fuse)) {
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file_start_write(passthrough_filp);
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ret = vfs_iter_write(passthrough_filp, iter, &iocb_fuse->ki_pos,
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iocb_to_rw_flags(iocb_fuse->ki_flags,
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PASSTHROUGH_IOCB_MASK));
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file_end_write(passthrough_filp);
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if (ret > 0)
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fuse_copyattr(fuse_filp, passthrough_filp);
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} else {
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struct fuse_aio_req *aio_req;
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aio_req = kmalloc(sizeof(struct fuse_aio_req), GFP_KERNEL);
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if (!aio_req) {
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ret = -ENOMEM;
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goto out;
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}
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file_start_write(passthrough_filp);
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__sb_writers_release(passthrough_inode->i_sb, SB_FREEZE_WRITE);
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aio_req->iocb_fuse = iocb_fuse;
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kiocb_clone(&aio_req->iocb, iocb_fuse, passthrough_filp);
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aio_req->iocb.ki_complete = fuse_aio_rw_complete;
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ret = call_write_iter(passthrough_filp, &aio_req->iocb, iter);
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if (ret != -EIOCBQUEUED)
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fuse_aio_cleanup_handler(aio_req);
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}
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out:
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revert_creds(old_cred);
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inode_unlock(fuse_inode);
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return ret;
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}
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ssize_t fuse_passthrough_mmap(struct file *file, struct vm_area_struct *vma)
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{
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int ret;
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const struct cred *old_cred;
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struct fuse_file *ff = file->private_data;
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struct file *passthrough_filp = ff->passthrough.filp;
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if (!passthrough_filp->f_op->mmap)
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return -ENODEV;
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if (WARN_ON(file != vma->vm_file))
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return -EIO;
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vma->vm_file = get_file(passthrough_filp);
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old_cred = override_creds(ff->passthrough.cred);
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ret = call_mmap(vma->vm_file, vma);
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revert_creds(old_cred);
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if (ret)
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fput(passthrough_filp);
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else
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fput(file);
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fuse_file_accessed(file, passthrough_filp);
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return ret;
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}
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int fuse_passthrough_open(struct fuse_dev *fud, u32 lower_fd)
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{
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int res;
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struct file *passthrough_filp;
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struct fuse_conn *fc = fud->fc;
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struct inode *passthrough_inode;
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struct super_block *passthrough_sb;
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struct fuse_passthrough *passthrough;
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if (!fc->passthrough)
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return -EPERM;
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passthrough_filp = fget(lower_fd);
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if (!passthrough_filp) {
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pr_err("FUSE: invalid file descriptor for passthrough.\n");
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return -EBADF;
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}
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if (!passthrough_filp->f_op->read_iter ||
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!passthrough_filp->f_op->write_iter) {
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pr_err("FUSE: passthrough file misses file operations.\n");
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res = -EBADF;
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goto err_free_file;
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}
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passthrough_inode = file_inode(passthrough_filp);
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passthrough_sb = passthrough_inode->i_sb;
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if (passthrough_sb->s_stack_depth >= FILESYSTEM_MAX_STACK_DEPTH) {
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pr_err("FUSE: fs stacking depth exceeded for passthrough\n");
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res = -EINVAL;
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goto err_free_file;
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}
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passthrough = kmalloc(sizeof(struct fuse_passthrough), GFP_KERNEL);
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if (!passthrough) {
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res = -ENOMEM;
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goto err_free_file;
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}
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passthrough->filp = passthrough_filp;
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passthrough->cred = prepare_creds();
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idr_preload(GFP_KERNEL);
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spin_lock(&fc->passthrough_req_lock);
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res = idr_alloc(&fc->passthrough_req, passthrough, 1, 0, GFP_ATOMIC);
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spin_unlock(&fc->passthrough_req_lock);
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idr_preload_end();
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if (res > 0)
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return res;
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fuse_passthrough_release(passthrough);
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kfree(passthrough);
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err_free_file:
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fput(passthrough_filp);
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return res;
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}
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int fuse_passthrough_setup(struct fuse_conn *fc, struct fuse_file *ff,
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struct fuse_open_out *openarg)
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{
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struct fuse_passthrough *passthrough;
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int passthrough_fh = openarg->passthrough_fh;
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if (!fc->passthrough)
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return -EPERM;
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/* Default case, passthrough is not requested */
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if (passthrough_fh <= 0)
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return -EINVAL;
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spin_lock(&fc->passthrough_req_lock);
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passthrough = idr_remove(&fc->passthrough_req, passthrough_fh);
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spin_unlock(&fc->passthrough_req_lock);
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if (!passthrough)
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return -EINVAL;
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ff->passthrough = *passthrough;
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kfree(passthrough);
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return 0;
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}
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void fuse_passthrough_release(struct fuse_passthrough *passthrough)
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{
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if (passthrough->filp) {
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fput(passthrough->filp);
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passthrough->filp = NULL;
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}
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if (passthrough->cred) {
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put_cred(passthrough->cred);
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passthrough->cred = NULL;
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}
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}
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