436 lines
9.0 KiB
C
436 lines
9.0 KiB
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_last(struct dentry *dentry, struct iattr *attr,
|
|
bool no_data)
|
|
{
|
|
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;
|
|
|
|
if (no_data)
|
|
stat.size = 0;
|
|
|
|
err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat, attr);
|
|
|
|
out_dput_parent:
|
|
dput(parent);
|
|
return err;
|
|
}
|
|
|
|
int ovl_setattr(struct dentry *dentry, struct iattr *attr)
|
|
{
|
|
int err;
|
|
struct dentry *upperdentry;
|
|
|
|
err = ovl_want_write(dentry);
|
|
if (err)
|
|
goto out;
|
|
|
|
upperdentry = ovl_dentry_upper(dentry);
|
|
if (upperdentry) {
|
|
mutex_lock(&upperdentry->d_inode->i_mutex);
|
|
err = notify_change(upperdentry, attr, NULL);
|
|
mutex_unlock(&upperdentry->d_inode->i_mutex);
|
|
} else {
|
|
err = ovl_copy_up_last(dentry, attr, false);
|
|
}
|
|
ovl_drop_write(dentry);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry,
|
|
struct kstat *stat)
|
|
{
|
|
struct path realpath;
|
|
|
|
ovl_path_real(dentry, &realpath);
|
|
return vfs_getattr(&realpath, stat);
|
|
}
|
|
|
|
int ovl_permission(struct inode *inode, int mask)
|
|
{
|
|
struct ovl_entry *oe;
|
|
struct dentry *alias = NULL;
|
|
struct inode *realinode;
|
|
struct dentry *realdentry;
|
|
bool is_upper;
|
|
int err;
|
|
|
|
if (S_ISDIR(inode->i_mode)) {
|
|
oe = inode->i_private;
|
|
} else if (mask & MAY_NOT_BLOCK) {
|
|
return -ECHILD;
|
|
} else {
|
|
/*
|
|
* For non-directories find an alias and get the info
|
|
* from there.
|
|
*/
|
|
alias = d_find_any_alias(inode);
|
|
if (WARN_ON(!alias))
|
|
return -ENOENT;
|
|
|
|
oe = alias->d_fsdata;
|
|
}
|
|
|
|
realdentry = ovl_entry_real(oe, &is_upper);
|
|
|
|
/* Careful in RCU walk mode */
|
|
realinode = ACCESS_ONCE(realdentry->d_inode);
|
|
if (!realinode) {
|
|
WARN_ON(!(mask & MAY_NOT_BLOCK));
|
|
err = -ENOENT;
|
|
goto out_dput;
|
|
}
|
|
|
|
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.
|
|
*/
|
|
err = -EROFS;
|
|
if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) &&
|
|
(S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
|
|
goto out_dput;
|
|
}
|
|
|
|
err = __inode_permission(realinode, mask);
|
|
out_dput:
|
|
dput(alias);
|
|
return err;
|
|
}
|
|
|
|
|
|
struct ovl_link_data {
|
|
struct dentry *realdentry;
|
|
void *cookie;
|
|
};
|
|
|
|
static const char *ovl_follow_link(struct dentry *dentry, void **cookie)
|
|
{
|
|
struct dentry *realdentry;
|
|
struct inode *realinode;
|
|
struct ovl_link_data *data = NULL;
|
|
const char *ret;
|
|
|
|
realdentry = ovl_dentry_real(dentry);
|
|
realinode = realdentry->d_inode;
|
|
|
|
if (WARN_ON(!realinode->i_op->follow_link))
|
|
return ERR_PTR(-EPERM);
|
|
|
|
if (realinode->i_op->put_link) {
|
|
data = kmalloc(sizeof(struct ovl_link_data), GFP_KERNEL);
|
|
if (!data)
|
|
return ERR_PTR(-ENOMEM);
|
|
data->realdentry = realdentry;
|
|
}
|
|
|
|
ret = realinode->i_op->follow_link(realdentry, cookie);
|
|
if (IS_ERR_OR_NULL(ret)) {
|
|
kfree(data);
|
|
return ret;
|
|
}
|
|
|
|
if (data)
|
|
data->cookie = *cookie;
|
|
|
|
*cookie = data;
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void ovl_put_link(struct inode *unused, void *c)
|
|
{
|
|
struct inode *realinode;
|
|
struct ovl_link_data *data = c;
|
|
|
|
if (!data)
|
|
return;
|
|
|
|
realinode = data->realdentry->d_inode;
|
|
realinode->i_op->put_link(realinode, data->cookie);
|
|
kfree(data);
|
|
}
|
|
|
|
static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
|
|
{
|
|
struct path realpath;
|
|
struct inode *realinode;
|
|
|
|
ovl_path_real(dentry, &realpath);
|
|
realinode = realpath.dentry->d_inode;
|
|
|
|
if (!realinode->i_op->readlink)
|
|
return -EINVAL;
|
|
|
|
touch_atime(&realpath);
|
|
|
|
return realinode->i_op->readlink(realpath.dentry, buf, bufsiz);
|
|
}
|
|
|
|
|
|
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, const char *name,
|
|
const void *value, size_t size, int flags)
|
|
{
|
|
int err;
|
|
struct dentry *upperdentry;
|
|
|
|
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);
|
|
err = vfs_setxattr(upperdentry, name, value, size, flags);
|
|
|
|
out_drop_write:
|
|
ovl_drop_write(dentry);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
static bool ovl_need_xattr_filter(struct dentry *dentry,
|
|
enum ovl_path_type type)
|
|
{
|
|
if ((type & (__OVL_PATH_PURE | __OVL_PATH_UPPER)) == __OVL_PATH_UPPER)
|
|
return S_ISDIR(dentry->d_inode->i_mode);
|
|
else
|
|
return false;
|
|
}
|
|
|
|
ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
|
|
void *value, size_t size)
|
|
{
|
|
struct path realpath;
|
|
enum ovl_path_type type = ovl_path_real(dentry, &realpath);
|
|
|
|
if (ovl_need_xattr_filter(dentry, type) && ovl_is_private_xattr(name))
|
|
return -ENODATA;
|
|
|
|
return vfs_getxattr(realpath.dentry, name, value, size);
|
|
}
|
|
|
|
ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
|
|
{
|
|
struct path realpath;
|
|
enum ovl_path_type type = ovl_path_real(dentry, &realpath);
|
|
ssize_t res;
|
|
int off;
|
|
|
|
res = vfs_listxattr(realpath.dentry, list, size);
|
|
if (res <= 0 || size == 0)
|
|
return res;
|
|
|
|
if (!ovl_need_xattr_filter(dentry, type))
|
|
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);
|
|
|
|
err = ovl_want_write(dentry);
|
|
if (err)
|
|
goto out;
|
|
|
|
err = -ENODATA;
|
|
if (ovl_need_xattr_filter(dentry, type) && 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);
|
|
}
|
|
|
|
err = vfs_removexattr(realpath.dentry, name);
|
|
out_drop_write:
|
|
ovl_drop_write(dentry);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
struct inode *ovl_d_select_inode(struct dentry *dentry, unsigned file_flags)
|
|
{
|
|
int err;
|
|
struct path realpath;
|
|
enum ovl_path_type type;
|
|
|
|
if (d_is_dir(dentry))
|
|
return d_backing_inode(dentry);
|
|
|
|
type = ovl_path_real(dentry, &realpath);
|
|
if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) {
|
|
err = ovl_want_write(dentry);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
|
|
if (file_flags & O_TRUNC)
|
|
err = ovl_copy_up_last(dentry, NULL, true);
|
|
else
|
|
err = ovl_copy_up(dentry);
|
|
ovl_drop_write(dentry);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
|
|
ovl_path_upper(dentry, &realpath);
|
|
}
|
|
|
|
if (realpath.dentry->d_flags & DCACHE_OP_SELECT_INODE)
|
|
return realpath.dentry->d_op->d_select_inode(realpath.dentry, file_flags);
|
|
|
|
return d_backing_inode(realpath.dentry);
|
|
}
|
|
|
|
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,
|
|
};
|
|
|
|
static const struct inode_operations ovl_symlink_inode_operations = {
|
|
.setattr = ovl_setattr,
|
|
.follow_link = ovl_follow_link,
|
|
.put_link = ovl_put_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;
|
|
|
|
mode &= S_IFMT;
|
|
|
|
inode->i_ino = get_next_ino();
|
|
inode->i_mode = mode;
|
|
inode->i_flags |= S_NOATIME | S_NOCMTIME;
|
|
|
|
switch (mode) {
|
|
case S_IFDIR:
|
|
inode->i_private = oe;
|
|
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;
|
|
}
|