481 lines
10 KiB
C
481 lines
10 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_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)
|
|
{
|
|
bool is_upper;
|
|
struct inode *realinode = ovl_inode_real(inode, &is_upper);
|
|
const struct cred *old_cred;
|
|
int err;
|
|
|
|
/* Careful in RCU walk mode */
|
|
if (!realinode) {
|
|
WARN_ON(!(mask & MAY_NOT_BLOCK));
|
|
return -ECHILD;
|
|
}
|
|
|
|
/*
|
|
* 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 && !special_file(realinode->i_mode) && mask & MAY_WRITE) {
|
|
mask &= ~(MAY_WRITE | MAY_APPEND);
|
|
/* Make sure mounter can read file for copy up later */
|
|
mask |= MAY_READ;
|
|
}
|
|
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;
|
|
|
|
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)
|
|
{
|
|
#define OVL_XATTR_PRE_NAME OVL_XATTR_PREFIX "."
|
|
return strncmp(name, OVL_XATTR_PRE_NAME,
|
|
sizeof(OVL_XATTR_PRE_NAME) - 1) == 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 = 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, NULL);
|
|
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;
|
|
}
|
|
|
|
int ovl_update_time(struct inode *inode, struct timespec *ts, int flags)
|
|
{
|
|
struct dentry *alias;
|
|
struct path upperpath;
|
|
|
|
if (!(flags & S_ATIME))
|
|
return 0;
|
|
|
|
alias = d_find_any_alias(inode);
|
|
if (!alias)
|
|
return 0;
|
|
|
|
ovl_path_upper(alias, &upperpath);
|
|
if (upperpath.dentry) {
|
|
touch_atime(&upperpath);
|
|
inode->i_atime = d_inode(upperpath.dentry)->i_atime;
|
|
}
|
|
|
|
dput(alias);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct inode_operations ovl_file_inode_operations = {
|
|
.setattr = ovl_setattr,
|
|
.permission = ovl_permission,
|
|
.getattr = ovl_getattr,
|
|
.setxattr = generic_setxattr,
|
|
.getxattr = ovl_getxattr,
|
|
.listxattr = ovl_listxattr,
|
|
.removexattr = ovl_removexattr,
|
|
.get_acl = ovl_get_acl,
|
|
.update_time = ovl_update_time,
|
|
};
|
|
|
|
static const struct inode_operations ovl_symlink_inode_operations = {
|
|
.setattr = ovl_setattr,
|
|
.get_link = ovl_get_link,
|
|
.readlink = ovl_readlink,
|
|
.getattr = ovl_getattr,
|
|
.setxattr = generic_setxattr,
|
|
.getxattr = ovl_getxattr,
|
|
.listxattr = ovl_listxattr,
|
|
.removexattr = ovl_removexattr,
|
|
.update_time = ovl_update_time,
|
|
};
|
|
|
|
static void ovl_fill_inode(struct inode *inode, umode_t mode)
|
|
{
|
|
inode->i_ino = get_next_ino();
|
|
inode->i_mode = mode;
|
|
inode->i_flags |= S_NOCMTIME;
|
|
|
|
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;
|
|
|
|
default:
|
|
WARN(1, "illegal file type: %i\n", mode);
|
|
/* Fall through */
|
|
|
|
case S_IFREG:
|
|
case S_IFSOCK:
|
|
case S_IFBLK:
|
|
case S_IFCHR:
|
|
case S_IFIFO:
|
|
inode->i_op = &ovl_file_inode_operations;
|
|
break;
|
|
}
|
|
}
|
|
|
|
struct inode *ovl_new_inode(struct super_block *sb, umode_t mode)
|
|
{
|
|
struct inode *inode;
|
|
|
|
inode = new_inode(sb);
|
|
if (inode)
|
|
ovl_fill_inode(inode, mode);
|
|
|
|
return inode;
|
|
}
|
|
|
|
static int ovl_inode_test(struct inode *inode, void *data)
|
|
{
|
|
return ovl_inode_real(inode, NULL) == data;
|
|
}
|
|
|
|
static int ovl_inode_set(struct inode *inode, void *data)
|
|
{
|
|
inode->i_private = (void *) (((unsigned long) data) | OVL_ISUPPER_MASK);
|
|
return 0;
|
|
}
|
|
|
|
struct inode *ovl_get_inode(struct super_block *sb, struct inode *realinode)
|
|
|
|
{
|
|
struct inode *inode;
|
|
|
|
inode = iget5_locked(sb, (unsigned long) realinode,
|
|
ovl_inode_test, ovl_inode_set, realinode);
|
|
if (inode && inode->i_state & I_NEW) {
|
|
ovl_fill_inode(inode, realinode->i_mode);
|
|
set_nlink(inode, realinode->i_nlink);
|
|
unlock_new_inode(inode);
|
|
}
|
|
|
|
return inode;
|
|
}
|