[deliverable/linux.git] / fs / overlayfs / inode.c

/*
 *
 * Copyright (C) 2011 Novell Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */

#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/xattr.h>
#include "overlayfs.h"

static int ovl_copy_up_truncate(struct dentry *dentry)
{
	int err;
	struct dentry *parent;
	struct kstat stat;
	struct path lowerpath;

	parent = dget_parent(dentry);
	err = ovl_copy_up(parent);
	if (err)
		goto out_dput_parent;

	ovl_path_lower(dentry, &lowerpath);
	err = vfs_getattr(&lowerpath, &stat);
	if (err)
		goto out_dput_parent;

	stat.size = 0;
	err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat);

out_dput_parent:
	dput(parent);
	return err;
}

int ovl_setattr(struct dentry *dentry, struct iattr *attr)
{
	int err;
	struct dentry *upperdentry;
	const struct cred *old_cred;

	/*
	 * Check for permissions before trying to copy-up.  This is redundant
	 * since it will be rechecked later by ->setattr() on upper dentry.  But
	 * without this, copy-up can be triggered by just about anybody.
	 *
	 * We don't initialize inode->size, which just means that
	 * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not
	 * check for a swapfile (which this won't be anyway).
	 */
	err = inode_change_ok(dentry->d_inode, attr);
	if (err)
		return err;

	err = ovl_want_write(dentry);
	if (err)
		goto out;

	if (attr->ia_valid & ATTR_SIZE) {
		struct inode *realinode = d_inode(ovl_dentry_real(dentry));

		err = -ETXTBSY;
		if (atomic_read(&realinode->i_writecount) < 0)
			goto out_drop_write;
	}

	err = ovl_copy_up(dentry);
	if (!err) {
		struct inode *winode = NULL;

		upperdentry = ovl_dentry_upper(dentry);

		if (attr->ia_valid & ATTR_SIZE) {
			winode = d_inode(upperdentry);
			err = get_write_access(winode);
			if (err)
				goto out_drop_write;
		}

		if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
			attr->ia_valid &= ~ATTR_MODE;

		inode_lock(upperdentry->d_inode);
		old_cred = ovl_override_creds(dentry->d_sb);
		err = notify_change(upperdentry, attr, NULL);
		revert_creds(old_cred);
		if (!err)
			ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
		inode_unlock(upperdentry->d_inode);

		if (winode)
			put_write_access(winode);
	}
out_drop_write:
	ovl_drop_write(dentry);
out:
	return err;
}

static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry,
			 struct kstat *stat)
{
	struct path realpath;
	const struct cred *old_cred;
	int err;

	ovl_path_real(dentry, &realpath);
	old_cred = ovl_override_creds(dentry->d_sb);
	err = vfs_getattr(&realpath, stat);
	revert_creds(old_cred);
	return err;
}

int ovl_permission(struct inode *inode, int mask)
{
	struct ovl_entry *oe = inode->i_private;
	bool is_upper;
	struct dentry *realdentry = ovl_entry_real(oe, &is_upper);
	struct inode *realinode;
	const struct cred *old_cred;
	int err;

	if (ovl_is_default_permissions(inode)) {
		struct kstat stat;
		struct path realpath = { .dentry = realdentry };

		if (mask & MAY_NOT_BLOCK)
			return -ECHILD;

		realpath.mnt = ovl_entry_mnt_real(oe, inode, is_upper);

		err = vfs_getattr(&realpath, &stat);
		if (err)
			return err;

		if ((stat.mode ^ inode->i_mode) & S_IFMT)
			return -ESTALE;

		inode->i_mode = stat.mode;
		inode->i_uid = stat.uid;
		inode->i_gid = stat.gid;

		return generic_permission(inode, mask);
	}

	/* Careful in RCU walk mode */
	realinode = d_inode_rcu(realdentry);
	if (!realinode) {
		WARN_ON(!(mask & MAY_NOT_BLOCK));
		return -ENOENT;
	}

	if (mask & MAY_WRITE) {
		umode_t mode = realinode->i_mode;

		/*
		 * Writes will always be redirected to upper layer, so
		 * ignore lower layer being read-only.
		 *
		 * If the overlay itself is read-only then proceed
		 * with the permission check, don't return EROFS.
		 * This will only happen if this is the lower layer of
		 * another overlayfs.
		 *
		 * If upper fs becomes read-only after the overlay was
		 * constructed return EROFS to prevent modification of
		 * upper layer.
		 */
		if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) &&
		    (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
			return -EROFS;
	}

	/*
	 * Check overlay inode with the creds of task and underlying inode
	 * with creds of mounter
	 */
	err = generic_permission(inode, mask);
	if (err)
		return err;

	old_cred = ovl_override_creds(inode->i_sb);
	if (!is_upper)
		mask &= ~(MAY_WRITE | MAY_APPEND);
	err = __inode_permission(realinode, mask);
	revert_creds(old_cred);

	return err;
}

static const char *ovl_get_link(struct dentry *dentry,
				struct inode *inode,
				struct delayed_call *done)
{
	struct dentry *realdentry;
	struct inode *realinode;
	const struct cred *old_cred;
	const char *p;

	if (!dentry)
		return ERR_PTR(-ECHILD);

	realdentry = ovl_dentry_real(dentry);
	realinode = realdentry->d_inode;

	if (WARN_ON(!realinode->i_op->get_link))
		return ERR_PTR(-EPERM);

	old_cred = ovl_override_creds(dentry->d_sb);
	p = realinode->i_op->get_link(realdentry, realinode, done);
	revert_creds(old_cred);
	return p;
}

static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
{
	struct path realpath;
	struct inode *realinode;
	const struct cred *old_cred;
	int err;

	ovl_path_real(dentry, &realpath);
	realinode = realpath.dentry->d_inode;

	if (!realinode->i_op->readlink)
		return -EINVAL;

	touch_atime(&realpath);

	old_cred = ovl_override_creds(dentry->d_sb);
	err = realinode->i_op->readlink(realpath.dentry, buf, bufsiz);
	revert_creds(old_cred);
	return err;
}

static bool ovl_is_private_xattr(const char *name)
{
	return strncmp(name, OVL_XATTR_PRE_NAME, OVL_XATTR_PRE_LEN) == 0;
}

int ovl_setxattr(struct dentry *dentry, struct inode *inode,
		 const char *name, const void *value,
		 size_t size, int flags)
{
	int err;
	struct dentry *upperdentry;
	const struct cred *old_cred;

	err = ovl_want_write(dentry);
	if (err)
		goto out;

	err = -EPERM;
	if (ovl_is_private_xattr(name))
		goto out_drop_write;

	err = ovl_copy_up(dentry);
	if (err)
		goto out_drop_write;

	upperdentry = ovl_dentry_upper(dentry);
	old_cred = ovl_override_creds(dentry->d_sb);
	err = vfs_setxattr(upperdentry, name, value, size, flags);
	revert_creds(old_cred);

out_drop_write:
	ovl_drop_write(dentry);
out:
	return err;
}

ssize_t ovl_getxattr(struct dentry *dentry, struct inode *inode,
		     const char *name, void *value, size_t size)
{
	struct dentry *realdentry = ovl_dentry_real(dentry);
	ssize_t res;
	const struct cred *old_cred;

	if (ovl_is_private_xattr(name))
		return -ENODATA;

	old_cred = ovl_override_creds(dentry->d_sb);
	res = vfs_getxattr(realdentry, name, value, size);
	revert_creds(old_cred);
	return res;
}

ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
{
	struct dentry *realdentry = ovl_dentry_real(dentry);
	ssize_t res;
	int off;
	const struct cred *old_cred;

	old_cred = ovl_override_creds(dentry->d_sb);
	res = vfs_listxattr(realdentry, list, size);
	revert_creds(old_cred);
	if (res <= 0 || size == 0)
		return res;

	/* filter out private xattrs */
	for (off = 0; off < res;) {
		char *s = list + off;
		size_t slen = strlen(s) + 1;

		BUG_ON(off + slen > res);

		if (ovl_is_private_xattr(s)) {
			res -= slen;
			memmove(s, s + slen, res - off);
		} else {
			off += slen;
		}
	}

	return res;
}

int ovl_removexattr(struct dentry *dentry, const char *name)
{
	int err;
	struct path realpath;
	enum ovl_path_type type = ovl_path_real(dentry, &realpath);
	const struct cred *old_cred;

	err = ovl_want_write(dentry);
	if (err)
		goto out;

	err = -ENODATA;
	if (ovl_is_private_xattr(name))
		goto out_drop_write;

	if (!OVL_TYPE_UPPER(type)) {
		err = vfs_getxattr(realpath.dentry, name, NULL, 0);
		if (err < 0)
			goto out_drop_write;

		err = ovl_copy_up(dentry);
		if (err)
			goto out_drop_write;

		ovl_path_upper(dentry, &realpath);
	}

	old_cred = ovl_override_creds(dentry->d_sb);
	err = vfs_removexattr(realpath.dentry, name);
	revert_creds(old_cred);
out_drop_write:
	ovl_drop_write(dentry);
out:
	return err;
}

struct posix_acl *ovl_get_acl(struct inode *inode, int type)
{
	struct inode *realinode = ovl_inode_real(inode);
	const struct cred *old_cred;
	struct posix_acl *acl;

	if (!IS_POSIXACL(realinode))
		return NULL;

	if (!realinode->i_op->get_acl)
		return NULL;

	old_cred = ovl_override_creds(inode->i_sb);
	acl = realinode->i_op->get_acl(realinode, type);
	revert_creds(old_cred);

	return acl;
}

static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
				  struct dentry *realdentry)
{
	if (OVL_TYPE_UPPER(type))
		return false;

	if (special_file(realdentry->d_inode->i_mode))
		return false;

	if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC))
		return false;

	return true;
}

int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags)
{
	int err = 0;
	struct path realpath;
	enum ovl_path_type type;

	type = ovl_path_real(dentry, &realpath);
	if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) {
		err = ovl_want_write(dentry);
		if (!err) {
			if (file_flags & O_TRUNC)
				err = ovl_copy_up_truncate(dentry);
			else
				err = ovl_copy_up(dentry);
			ovl_drop_write(dentry);
		}
	}

	return err;
}

static const struct inode_operations ovl_file_inode_operations = {
	.setattr	= ovl_setattr,
	.permission	= ovl_permission,
	.getattr	= ovl_getattr,
	.setxattr	= ovl_setxattr,
	.getxattr	= ovl_getxattr,
	.listxattr	= ovl_listxattr,
	.removexattr	= ovl_removexattr,
	.get_acl	= ovl_get_acl,
};

static const struct inode_operations ovl_symlink_inode_operations = {
	.setattr	= ovl_setattr,
	.get_link	= ovl_get_link,
	.readlink	= ovl_readlink,
	.getattr	= ovl_getattr,
	.setxattr	= ovl_setxattr,
	.getxattr	= ovl_getxattr,
	.listxattr	= ovl_listxattr,
	.removexattr	= ovl_removexattr,
};

struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
			    struct ovl_entry *oe)
{
	struct inode *inode;

	inode = new_inode(sb);
	if (!inode)
		return NULL;

	inode->i_ino = get_next_ino();
	inode->i_mode = mode;
	inode->i_flags |= S_NOATIME | S_NOCMTIME;
	inode->i_private = oe;

	mode &= S_IFMT;
	switch (mode) {
	case S_IFDIR:
		inode->i_op = &ovl_dir_inode_operations;
		inode->i_fop = &ovl_dir_operations;
		break;

	case S_IFLNK:
		inode->i_op = &ovl_symlink_inode_operations;
		break;

	case S_IFREG:
	case S_IFSOCK:
	case S_IFBLK:
	case S_IFCHR:
	case S_IFIFO:
		inode->i_op = &ovl_file_inode_operations;
		break;

	default:
		WARN(1, "illegal file type: %i\n", mode);
		iput(inode);
		inode = NULL;
	}

	return inode;
}
Commit	Line	Data
e9be9d5e MS	1	/*
	2	*
	3	* Copyright (C) 2011 Novell Inc.
	4	*
	5	* This program is free software; you can redistribute it and/or modify it
	6	* under the terms of the GNU General Public License version 2 as published by
	7	* the Free Software Foundation.
	8	*/
	9
	10	#include <linux/fs.h>
	11	#include <linux/slab.h>
	12	#include <linux/xattr.h>
	13	#include "overlayfs.h"
	14
0f7ff2da	15	static int ovl_copy_up_truncate(struct dentry *dentry)
e9be9d5e MS	16	{
	17	int err;
	18	struct dentry *parent;
	19	struct kstat stat;
	20	struct path lowerpath;
	21
	22	parent = dget_parent(dentry);
	23	err = ovl_copy_up(parent);
	24	if (err)
	25	goto out_dput_parent;
	26
	27	ovl_path_lower(dentry, &lowerpath);
	28	err = vfs_getattr(&lowerpath, &stat);
	29	if (err)
	30	goto out_dput_parent;
	31
0f7ff2da AV	32	stat.size = 0;
0f7ff2da AV	33	err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat);
e9be9d5e MS	34
	35	out_dput_parent:
	36	dput(parent);
	37	return err;
	38	}
	39
	40	int ovl_setattr(struct dentry dentry, struct iattr attr)
	41	{
	42	int err;
	43	struct dentry *upperdentry;
1175b6b8	44	const struct cred *old_cred;
e9be9d5e	45
cf9a6784 MS	46	/*
	47	* Check for permissions before trying to copy-up. This is redundant
	48	* since it will be rechecked later by ->setattr() on upper dentry. But
	49	* without this, copy-up can be triggered by just about anybody.
	50	*
	51	* We don't initialize inode->size, which just means that
	52	* inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not
	53	* check for a swapfile (which this won't be anyway).
	54	*/
	55	err = inode_change_ok(dentry->d_inode, attr);
	56	if (err)
	57	return err;
	58
e9be9d5e MS	59	err = ovl_want_write(dentry);
	60	if (err)
	61	goto out;
	62
03bea604 MS	63	if (attr->ia_valid & ATTR_SIZE) {
	64	struct inode *realinode = d_inode(ovl_dentry_real(dentry));
	65
	66	err = -ETXTBSY;
	67	if (atomic_read(&realinode->i_writecount) < 0)
	68	goto out_drop_write;
	69	}
	70
acff81ec MS	71	err = ovl_copy_up(dentry);
acff81ec MS	72	if (!err) {
03bea604 MS	73	struct inode *winode = NULL;
03bea604 MS	74
acff81ec MS	75	upperdentry = ovl_dentry_upper(dentry);
acff81ec MS	76
03bea604 MS	77	if (attr->ia_valid & ATTR_SIZE) {
	78	winode = d_inode(upperdentry);
	79	err = get_write_access(winode);
	80	if (err)
	81	goto out_drop_write;
	82	}
	83
b99c2d91 MS	84	if (attr->ia_valid & (ATTR_KILL_SUID\|ATTR_KILL_SGID))
	85	attr->ia_valid &= ~ATTR_MODE;
	86
5955102c	87	inode_lock(upperdentry->d_inode);
1175b6b8	88	old_cred = ovl_override_creds(dentry->d_sb);
e9be9d5e	89	err = notify_change(upperdentry, attr, NULL);
1175b6b8	90	revert_creds(old_cred);
b81de061 KK	91	if (!err)
b81de061 KK	92	ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
5955102c	93	inode_unlock(upperdentry->d_inode);
03bea604 MS	94
	95	if (winode)
	96	put_write_access(winode);
e9be9d5e	97	}
03bea604	98	out_drop_write:
e9be9d5e MS	99	ovl_drop_write(dentry);
	100	out:
	101	return err;
	102	}
	103
	104	static int ovl_getattr(struct vfsmount mnt, struct dentry dentry,
	105	struct kstat *stat)
	106	{
	107	struct path realpath;
1175b6b8 VG	108	const struct cred *old_cred;
1175b6b8 VG	109	int err;
e9be9d5e MS	110
e9be9d5e MS	111	ovl_path_real(dentry, &realpath);
1175b6b8 VG	112	old_cred = ovl_override_creds(dentry->d_sb);
	113	err = vfs_getattr(&realpath, stat);
	114	revert_creds(old_cred);
	115	return err;
e9be9d5e MS	116	}
	117
	118	int ovl_permission(struct inode *inode, int mask)
	119	{
58ed4e70	120	struct ovl_entry *oe = inode->i_private;
e9be9d5e	121	bool is_upper;
58ed4e70 AG	122	struct dentry *realdentry = ovl_entry_real(oe, &is_upper);
58ed4e70 AG	123	struct inode *realinode;
c0ca3d70	124	const struct cred *old_cred;
e9be9d5e MS	125	int err;
e9be9d5e MS	126
8d3095f4 MS	127	if (ovl_is_default_permissions(inode)) {
	128	struct kstat stat;
	129	struct path realpath = { .dentry = realdentry };
	130
	131	if (mask & MAY_NOT_BLOCK)
	132	return -ECHILD;
	133
	134	realpath.mnt = ovl_entry_mnt_real(oe, inode, is_upper);
	135
	136	err = vfs_getattr(&realpath, &stat);
	137	if (err)
58ed4e70	138	return err;
8d3095f4 MS	139
8d3095f4 MS	140	if ((stat.mode ^ inode->i_mode) & S_IFMT)
58ed4e70	141	return -ESTALE;
8d3095f4 MS	142
	143	inode->i_mode = stat.mode;
	144	inode->i_uid = stat.uid;
	145	inode->i_gid = stat.gid;
	146
58ed4e70	147	return generic_permission(inode, mask);
8d3095f4 MS	148	}
8d3095f4 MS	149
e9be9d5e	150	/* Careful in RCU walk mode */
58ed4e70	151	realinode = d_inode_rcu(realdentry);
e9be9d5e MS	152	if (!realinode) {
e9be9d5e MS	153	WARN_ON(!(mask & MAY_NOT_BLOCK));
58ed4e70	154	return -ENOENT;
e9be9d5e MS	155	}
	156
	157	if (mask & MAY_WRITE) {
	158	umode_t mode = realinode->i_mode;
	159
	160	/*
	161	* Writes will always be redirected to upper layer, so
	162	* ignore lower layer being read-only.
	163	*
	164	* If the overlay itself is read-only then proceed
	165	* with the permission check, don't return EROFS.
	166	* This will only happen if this is the lower layer of
	167	* another overlayfs.
	168	*
	169	* If upper fs becomes read-only after the overlay was
	170	* constructed return EROFS to prevent modification of
	171	* upper layer.
	172	*/
e9be9d5e MS	173	if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) &&
e9be9d5e MS	174	(S_ISREG(mode) \|\| S_ISDIR(mode) \|\| S_ISLNK(mode)))
58ed4e70	175	return -EROFS;
e9be9d5e MS	176	}
e9be9d5e MS	177
c0ca3d70 VG	178	/*
	179	* Check overlay inode with the creds of task and underlying inode
	180	* with creds of mounter
	181	*/
	182	err = generic_permission(inode, mask);
	183	if (err)
	184	return err;
	185
	186	old_cred = ovl_override_creds(inode->i_sb);
754f8cb7 VG	187	if (!is_upper)
754f8cb7 VG	188	mask &= ~(MAY_WRITE \| MAY_APPEND);
c0ca3d70 VG	189	err = __inode_permission(realinode, mask);
	190	revert_creds(old_cred);
	191
	192	return err;
e9be9d5e MS	193	}
e9be9d5e MS	194
6b255391	195	static const char ovl_get_link(struct dentry dentry,
fceef393 AV	196	struct inode *inode,
fceef393 AV	197	struct delayed_call *done)
e9be9d5e	198	{
e9be9d5e MS	199	struct dentry *realdentry;
e9be9d5e MS	200	struct inode *realinode;
1175b6b8 VG	201	const struct cred *old_cred;
1175b6b8 VG	202	const char *p;
e9be9d5e	203
6b255391 AV	204	if (!dentry)
	205	return ERR_PTR(-ECHILD);
	206
e9be9d5e MS	207	realdentry = ovl_dentry_real(dentry);
	208	realinode = realdentry->d_inode;
	209
6b255391	210	if (WARN_ON(!realinode->i_op->get_link))
e9be9d5e MS	211	return ERR_PTR(-EPERM);
e9be9d5e MS	212
1175b6b8 VG	213	old_cred = ovl_override_creds(dentry->d_sb);
	214	p = realinode->i_op->get_link(realdentry, realinode, done);
	215	revert_creds(old_cred);
	216	return p;
e9be9d5e MS	217	}
	218
	219	static int ovl_readlink(struct dentry dentry, char __user buf, int bufsiz)
	220	{
	221	struct path realpath;
	222	struct inode *realinode;
1175b6b8 VG	223	const struct cred *old_cred;
1175b6b8 VG	224	int err;
e9be9d5e MS	225
	226	ovl_path_real(dentry, &realpath);
	227	realinode = realpath.dentry->d_inode;
	228
	229	if (!realinode->i_op->readlink)
	230	return -EINVAL;
	231
	232	touch_atime(&realpath);
	233
1175b6b8 VG	234	old_cred = ovl_override_creds(dentry->d_sb);
	235	err = realinode->i_op->readlink(realpath.dentry, buf, bufsiz);
	236	revert_creds(old_cred);
	237	return err;
e9be9d5e MS	238	}
e9be9d5e MS	239
e9be9d5e MS	240	static bool ovl_is_private_xattr(const char *name)
e9be9d5e MS	241	{
cead89bb	242	return strncmp(name, OVL_XATTR_PRE_NAME, OVL_XATTR_PRE_LEN) == 0;
e9be9d5e MS	243	}
e9be9d5e MS	244
3767e255 AV	245	int ovl_setxattr(struct dentry dentry, struct inode inode,
	246	const char name, const void value,
	247	size_t size, int flags)
e9be9d5e MS	248	{
	249	int err;
	250	struct dentry *upperdentry;
1175b6b8	251	const struct cred *old_cred;
e9be9d5e MS	252
	253	err = ovl_want_write(dentry);
	254	if (err)
	255	goto out;
	256
	257	err = -EPERM;
	258	if (ovl_is_private_xattr(name))
	259	goto out_drop_write;
	260
	261	err = ovl_copy_up(dentry);
	262	if (err)
	263	goto out_drop_write;
	264
	265	upperdentry = ovl_dentry_upper(dentry);
1175b6b8	266	old_cred = ovl_override_creds(dentry->d_sb);
e9be9d5e	267	err = vfs_setxattr(upperdentry, name, value, size, flags);
1175b6b8	268	revert_creds(old_cred);
e9be9d5e MS	269
	270	out_drop_write:
	271	ovl_drop_write(dentry);
	272	out:
	273	return err;
	274	}
	275
ce23e640 AV	276	ssize_t ovl_getxattr(struct dentry dentry, struct inode inode,
ce23e640 AV	277	const char name, void value, size_t size)
e9be9d5e	278	{
b581755b	279	struct dentry *realdentry = ovl_dentry_real(dentry);
1175b6b8 VG	280	ssize_t res;
1175b6b8 VG	281	const struct cred *old_cred;
52148463	282
b581755b	283	if (ovl_is_private_xattr(name))
e9be9d5e MS	284	return -ENODATA;
e9be9d5e MS	285
1175b6b8 VG	286	old_cred = ovl_override_creds(dentry->d_sb);
	287	res = vfs_getxattr(realdentry, name, value, size);
	288	revert_creds(old_cred);
	289	return res;
e9be9d5e MS	290	}
	291
	292	ssize_t ovl_listxattr(struct dentry dentry, char list, size_t size)
	293	{
b581755b	294	struct dentry *realdentry = ovl_dentry_real(dentry);
e9be9d5e MS	295	ssize_t res;
e9be9d5e MS	296	int off;
1175b6b8	297	const struct cred *old_cred;
e9be9d5e	298
1175b6b8	299	old_cred = ovl_override_creds(dentry->d_sb);
b581755b	300	res = vfs_listxattr(realdentry, list, size);
1175b6b8	301	revert_creds(old_cred);
e9be9d5e MS	302	if (res <= 0 \|\| size == 0)
	303	return res;
	304
e9be9d5e MS	305	/* filter out private xattrs */
	306	for (off = 0; off < res;) {
	307	char *s = list + off;
	308	size_t slen = strlen(s) + 1;
	309
	310	BUG_ON(off + slen > res);
	311
	312	if (ovl_is_private_xattr(s)) {
	313	res -= slen;
	314	memmove(s, s + slen, res - off);
	315	} else {
	316	off += slen;
	317	}
	318	}
	319
	320	return res;
	321	}
	322
	323	int ovl_removexattr(struct dentry dentry, const char name)
	324	{
	325	int err;
	326	struct path realpath;
52148463	327	enum ovl_path_type type = ovl_path_real(dentry, &realpath);
1175b6b8	328	const struct cred *old_cred;
e9be9d5e MS	329
	330	err = ovl_want_write(dentry);
	331	if (err)
	332	goto out;
	333
52148463	334	err = -ENODATA;
b581755b	335	if (ovl_is_private_xattr(name))
e9be9d5e MS	336	goto out_drop_write;
e9be9d5e MS	337
1afaba1e	338	if (!OVL_TYPE_UPPER(type)) {
e9be9d5e MS	339	err = vfs_getxattr(realpath.dentry, name, NULL, 0);
	340	if (err < 0)
	341	goto out_drop_write;
	342
	343	err = ovl_copy_up(dentry);
	344	if (err)
	345	goto out_drop_write;
	346
	347	ovl_path_upper(dentry, &realpath);
	348	}
	349
1175b6b8	350	old_cred = ovl_override_creds(dentry->d_sb);
e9be9d5e	351	err = vfs_removexattr(realpath.dentry, name);
1175b6b8	352	revert_creds(old_cred);
e9be9d5e MS	353	out_drop_write:
	354	ovl_drop_write(dentry);
	355	out:
	356	return err;
	357	}
	358
39a25b2b VG	359	struct posix_acl ovl_get_acl(struct inode inode, int type)
	360	{
	361	struct inode *realinode = ovl_inode_real(inode);
1175b6b8 VG	362	const struct cred *old_cred;
1175b6b8 VG	363	struct posix_acl *acl;
39a25b2b	364
39a25b2b VG	365	if (!IS_POSIXACL(realinode))
	366	return NULL;
	367
	368	if (!realinode->i_op->get_acl)
	369	return NULL;
	370
1175b6b8 VG	371	old_cred = ovl_override_creds(inode->i_sb);
	372	acl = realinode->i_op->get_acl(realinode, type);
	373	revert_creds(old_cred);
	374
	375	return acl;
39a25b2b VG	376	}
39a25b2b VG	377
e9be9d5e MS	378	static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
	379	struct dentry *realdentry)
	380	{
1afaba1e	381	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	382	return false;
	383
	384	if (special_file(realdentry->d_inode->i_mode))
	385	return false;
	386
	387	if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC))
	388	return false;
	389
	390	return true;
	391	}
	392
2d902671	393	int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags)
e9be9d5e	394	{
2d902671	395	int err = 0;
e9be9d5e MS	396	struct path realpath;
e9be9d5e MS	397	enum ovl_path_type type;
e9be9d5e MS	398
e9be9d5e MS	399	type = ovl_path_real(dentry, &realpath);
4bacc9c9	400	if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) {
e9be9d5e	401	err = ovl_want_write(dentry);
2d902671 MS	402	if (!err) {
	403	if (file_flags & O_TRUNC)
	404	err = ovl_copy_up_truncate(dentry);
	405	else
	406	err = ovl_copy_up(dentry);
	407	ovl_drop_write(dentry);
	408	}
e9be9d5e MS	409	}
e9be9d5e MS	410
2d902671	411	return err;
e9be9d5e MS	412	}
	413
	414	static const struct inode_operations ovl_file_inode_operations = {
	415	.setattr = ovl_setattr,
	416	.permission = ovl_permission,
	417	.getattr = ovl_getattr,
	418	.setxattr = ovl_setxattr,
	419	.getxattr = ovl_getxattr,
	420	.listxattr = ovl_listxattr,
	421	.removexattr = ovl_removexattr,
39a25b2b	422	.get_acl = ovl_get_acl,
e9be9d5e MS	423	};
	424
	425	static const struct inode_operations ovl_symlink_inode_operations = {
	426	.setattr = ovl_setattr,
6b255391	427	.get_link = ovl_get_link,
e9be9d5e MS	428	.readlink = ovl_readlink,
	429	.getattr = ovl_getattr,
	430	.setxattr = ovl_setxattr,
	431	.getxattr = ovl_getxattr,
	432	.listxattr = ovl_listxattr,
	433	.removexattr = ovl_removexattr,
	434	};
	435
	436	struct inode ovl_new_inode(struct super_block sb, umode_t mode,
	437	struct ovl_entry *oe)
	438	{
	439	struct inode *inode;
	440
	441	inode = new_inode(sb);
	442	if (!inode)
	443	return NULL;
	444
e9be9d5e MS	445	inode->i_ino = get_next_ino();
	446	inode->i_mode = mode;
	447	inode->i_flags \|= S_NOATIME \| S_NOCMTIME;
58ed4e70	448	inode->i_private = oe;
e9be9d5e	449
07a2daab	450	mode &= S_IFMT;
e9be9d5e MS	451	switch (mode) {
e9be9d5e MS	452	case S_IFDIR:
e9be9d5e MS	453	inode->i_op = &ovl_dir_inode_operations;
	454	inode->i_fop = &ovl_dir_operations;
	455	break;
	456
	457	case S_IFLNK:
	458	inode->i_op = &ovl_symlink_inode_operations;
	459	break;
	460
	461	case S_IFREG:
	462	case S_IFSOCK:
	463	case S_IFBLK:
	464	case S_IFCHR:
	465	case S_IFIFO:
	466	inode->i_op = &ovl_file_inode_operations;
	467	break;
	468
	469	default:
	470	WARN(1, "illegal file type: %i\n", mode);
	471	iput(inode);
	472	inode = NULL;
	473	}
	474
	475	return inode;
e9be9d5e	476	}