path: root/fs/xfs/linux-2.6/xfs_ioctl.c

/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_alloc.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_ioctl.h"
#include "xfs_rtalloc.h"
#include "xfs_itable.h"
#include "xfs_error.h"
#include "xfs_attr.h"
#include "xfs_bmap.h"
#include "xfs_buf_item.h"
#include "xfs_utils.h"
#include "xfs_dfrag.h"
#include "xfs_fsops.h"
#include "xfs_vnodeops.h"
#include "xfs_quota.h"
#include "xfs_inode_item.h"
#include "xfs_export.h"
#include "xfs_trace.h"

#include <linux/capability.h>
#include <linux/dcache.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/exportfs.h>

/*
 * xfs_find_handle maps from userspace xfs_fsop_handlereq structure to
 * a file or fs handle.
 *
 * XFS_IOC_PATH_TO_FSHANDLE
 *    returns fs handle for a mount point or path within that mount point
 * XFS_IOC_FD_TO_HANDLE
 *    returns full handle for a FD opened in user space
 * XFS_IOC_PATH_TO_HANDLE
 *    returns full handle for a path
 */
int
xfs_find_handle(
	unsigned int		cmd,
	xfs_fsop_handlereq_t	*hreq)
{
	int			hsize;
	xfs_handle_t		handle;
	struct inode		*inode;
	struct file		*file = NULL;
	struct path		path;
	int			error;
	struct xfs_inode	*ip;

	if (cmd == XFS_IOC_FD_TO_HANDLE) {
		file = fget(hreq->fd);
		if (!file)
			return -EBADF;
		inode = file->f_path.dentry->d_inode;
	} else {
		error = user_lpath((const char __user *)hreq->path, &path);
		if (error)
			return error;
		inode = path.dentry->d_inode;
	}
	ip = XFS_I(inode);

	/*
	 * We can only generate handles for inodes residing on a XFS filesystem,
	 * and only for regular files, directories or symbolic links.
	 */
	error = -EINVAL;
	if (inode->i_sb->s_magic != XFS_SB_MAGIC)
		goto out_put;

	error = -EBADF;
	if (!S_ISREG(inode->i_mode) &&
	    !S_ISDIR(inode->i_mode) &&
	    !S_ISLNK(inode->i_mode))
		goto out_put;


	memcpy(&handle.ha_fsid, ip->i_mount->m_fixedfsid, sizeof(xfs_fsid_t));

	if (cmd == XFS_IOC_PATH_TO_FSHANDLE) {
		/*
		 * This handle only contains an fsid, zero the rest.
		 */
		memset(&handle.ha_fid, 0, sizeof(handle.ha_fid));
		hsize = sizeof(xfs_fsid_t);
	} else {
		int		lock_mode;

		lock_mode = xfs_ilock_map_shared(ip);
		handle.ha_fid.fid_len = sizeof(xfs_fid_t) -
					sizeof(handle.ha_fid.fid_len);
		handle.ha_fid.fid_pad = 0;
		handle.ha_fid.fid_gen = ip->i_d.di_gen;
		handle.ha_fid.fid_ino = ip->i_ino;
		xfs_iunlock_map_shared(ip, lock_mode);

		hsize = XFS_HSIZE(handle);
	}

	error = -EFAULT;
	if (copy_to_user(hreq->ohandle, &handle, hsize) ||
	    copy_to_user(hreq->ohandlen, &hsize, sizeof(__s32)))
		goto out_put;

	error = 0;

 out_put:
	if (cmd == XFS_IOC_FD_TO_HANDLE)
		fput(file);
	else
		path_put(&path);
	return error;
}

/*
 * No need to do permission checks on the various pathname components
 * as the handle operations are privileged.
 */
STATIC int
xfs_handle_acceptable(
	void			*context,
	struct dentry		*dentry)
{
	return 1;
}

/*
 * Convert userspace handle data into a dentry.
 */
struct dentry *
xfs_handle_to_dentry(
	struct file		*parfilp,
	void __user		*uhandle,
	u32			hlen)
{
	xfs_handle_t		handle;
	struct xfs_fid64	fid;

	/*
	 * Only allow handle opens under a directory.
	 */
	if (!S_ISDIR(parfilp->f_path.dentry->d_inode->i_mode))
		return ERR_PTR(-ENOTDIR);

	if (hlen != sizeof(xfs_handle_t))
		return ERR_PTR(-EINVAL);
	if (copy_from_user(&handle, uhandle, hlen))
		return ERR_PTR(-EFAULT);
	if (handle.ha_fid.fid_len !=
	    sizeof(handle.ha_fid) - sizeof(handle.ha_fid.fid_len))
		return ERR_PTR(-EINVAL);

	memset(&fid, 0, sizeof(struct fid));
	fid.ino = handle.ha_fid.fid_ino;
	fid.gen = handle.ha_fid.fid_gen;

	return exportfs_decode_fh(parfilp->f_path.mnt, (struct fid *)&fid, 3,
			FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG,
			xfs_handle_acceptable, NULL);
}

STATIC struct dentry *
xfs_handlereq_to_dentry(
	struct file		*parfilp,
	xfs_fsop_handlereq_t	*hreq)
{
	return xfs_handle_to_dentry(parfilp, hreq->ihandle, hreq->ihandlen);
}

int
xfs_open_by_handle(
	struct file		*parfilp,
	xfs_fsop_handlereq_t	*hreq)
{
	const struct cred	*cred = current_cred();
	int			error;
	int			fd;
	int			permflag;
	struct file		*filp;
	struct inode		*inode;
	struct dentry		*dentry;

	if (!capable(CAP_SYS_ADMIN))
		return -XFS_ERROR(EPERM);

	dentry = xfs_handlereq_to_dentry(parfilp, hreq);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);
	inode = dentry->d_inode;

	/* Restrict xfs_open_by_handle to directories & regular files. */
	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))) {
		error = -XFS_ERROR(EPERM);
		goto out_dput;
	}

#if BITS_PER_LONG != 32
	hreq->oflags |= O_LARGEFILE;
#endif

	/* Put open permission in namei format. */
	permflag = hreq->oflags;
	if ((permflag+1) & O_ACCMODE)
		permflag++;
	if (permflag & O_TRUNC)
		permflag |= 2;

	if ((!(permflag & O_APPEND) || (permflag & O_TRUNC)) &&
	    (permflag & FMODE_WRITE) && IS_APPEND(inode)) {
		error = -XFS_ERROR(EPERM);
		goto out_dput;
	}

	if ((permflag & FMODE_WRITE) && IS_IMMUTABLE(inode)) {
		error = -XFS_ERROR(EACCES);
		goto out_dput;
	}

	/* Can't write directories. */
	if (S_ISDIR(inode->i_mode) && (permflag & FMODE_WRITE)) {
		error = -XFS_ERROR(EISDIR);
		goto out_dput;
	}

	fd = get_unused_fd();
	if (fd < 0) {
		error = fd;
		goto out_dput;
	}

	filp = dentry_open(dentry, mntget(parfilp->f_path.mnt),
			   hreq->oflags, cred);
	if (IS_ERR(filp)) {
		put_unused_fd(fd);
		return PTR_ERR(filp);
	}

	if (inode->i_mode & S_IFREG) {
		filp->f_flags |= O_NOATIME;
		filp->f_mode |= FMODE_NOCMTIME;
	}

	fd_install(fd, filp);
	return fd;

 out_dput:
	dput(dentry);
	return error;
}

/*
 * This is a copy from fs/namei.c:vfs_readlink(), except for removing it's
 * unused first argument.
 */
STATIC int
do_readlink(
	char __user		*buffer,
	int			buflen,
	const char		*link)
{
        int len;

	len = PTR_ERR(link);
	if (IS_ERR(link))
		goto out;

	len = strlen(link);
	if (len > (unsigned) buflen)
		len = buflen;
	if (copy_to_user(buffer, link, len))
		len = -EFAULT;
 out:
	return len;
}


int
xfs_readlink_by_handle(
	struct file		*parfilp,
	xfs_fsop_handlereq_t	*hreq)
{
	struct dentry		*dentry;
	__u32			olen;
	void			*link;
	int			error;

	if (!capable(CAP_SYS_ADMIN))
		return -XFS_ERROR(EPERM);

	dentry = xfs_handlereq_to_dentry(parfilp, hreq);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

	/* Restrict this handle operation to symlinks only. */
	if (!S_ISLNK(dentry->d_inode->i_mode)) {
		error = -XFS_ERROR(EINVAL);
		goto out_dput;
	}

	if (copy_from_user(&olen, hreq->ohandlen, sizeof(__u32))) {
		error = -XFS_ERROR(EFAULT);
		goto out_dput;
	}

	link = kmalloc(MAXPATHLEN+1, GFP_KERNEL);
	if (!link) {
		error = -XFS_ERROR(ENOMEM);
		goto out_dput;
	}

	error = -xfs_readlink(XFS_I(dentry->d_inode), link);
	if (error)
		g