108 lines
3.0 KiB
C
108 lines
3.0 KiB
C
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#include <linux/syscalls.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/exportfs.h>
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#include <asm/uaccess.h>
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#include "internal.h"
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static long do_sys_name_to_handle(struct path *path,
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struct file_handle __user *ufh,
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int __user *mnt_id)
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{
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long retval;
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struct file_handle f_handle;
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int handle_dwords, handle_bytes;
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struct file_handle *handle = NULL;
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/*
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* We need t make sure wether the file system
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* support decoding of the file handle
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*/
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if (!path->mnt->mnt_sb->s_export_op ||
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!path->mnt->mnt_sb->s_export_op->fh_to_dentry)
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return -EOPNOTSUPP;
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if (copy_from_user(&f_handle, ufh, sizeof(struct file_handle)))
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return -EFAULT;
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if (f_handle.handle_bytes > MAX_HANDLE_SZ)
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return -EINVAL;
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handle = kmalloc(sizeof(struct file_handle) + f_handle.handle_bytes,
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GFP_KERNEL);
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if (!handle)
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return -ENOMEM;
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/* convert handle size to multiple of sizeof(u32) */
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handle_dwords = f_handle.handle_bytes >> 2;
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/* we ask for a non connected handle */
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retval = exportfs_encode_fh(path->dentry,
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(struct fid *)handle->f_handle,
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&handle_dwords, 0);
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handle->handle_type = retval;
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/* convert handle size to bytes */
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handle_bytes = handle_dwords * sizeof(u32);
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handle->handle_bytes = handle_bytes;
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if ((handle->handle_bytes > f_handle.handle_bytes) ||
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(retval == 255) || (retval == -ENOSPC)) {
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/* As per old exportfs_encode_fh documentation
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* we could return ENOSPC to indicate overflow
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* But file system returned 255 always. So handle
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* both the values
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*/
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/*
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* set the handle size to zero so we copy only
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* non variable part of the file_handle
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*/
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handle_bytes = 0;
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retval = -EOVERFLOW;
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} else
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retval = 0;
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/* copy the mount id */
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if (copy_to_user(mnt_id, &path->mnt->mnt_id, sizeof(*mnt_id)) ||
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copy_to_user(ufh, handle,
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sizeof(struct file_handle) + handle_bytes))
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retval = -EFAULT;
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kfree(handle);
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return retval;
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}
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/**
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* sys_name_to_handle_at: convert name to handle
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* @dfd: directory relative to which name is interpreted if not absolute
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* @name: name that should be converted to handle.
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* @handle: resulting file handle
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* @mnt_id: mount id of the file system containing the file
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* @flag: flag value to indicate whether to follow symlink or not
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*
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* @handle->handle_size indicate the space available to store the
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* variable part of the file handle in bytes. If there is not
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* enough space, the field is updated to return the minimum
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* value required.
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*/
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SYSCALL_DEFINE5(name_to_handle_at, int, dfd, const char __user *, name,
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struct file_handle __user *, handle, int __user *, mnt_id,
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int, flag)
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{
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struct path path;
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int lookup_flags;
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int err;
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if ((flag & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
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return -EINVAL;
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lookup_flags = (flag & AT_SYMLINK_FOLLOW) ? LOOKUP_FOLLOW : 0;
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if (flag & AT_EMPTY_PATH)
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lookup_flags |= LOOKUP_EMPTY;
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err = user_path_at(dfd, name, lookup_flags, &path);
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if (!err) {
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err = do_sys_name_to_handle(&path, handle, mnt_id);
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path_put(&path);
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}
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return err;
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}
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