/*
*
* 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/module.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/splice.h>
#include <linux/xattr.h>
#include <linux/security.h>
#include <linux/uaccess.h>
#include <linux/sched/signal.h>
#include <linux/cred.h>
#include <linux/namei.h>
#include <linux/fdtable.h>
#include <linux/ratelimit.h>
#include <linux/exportfs.h>
#include "overlayfs.h"
#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
static bool __read_mostly ovl_check_copy_up;
module_param_named(check_copy_up, ovl_check_copy_up, bool,
S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(ovl_check_copy_up,
"Warn on copy-up when causing process also has a R/O fd open");
static int ovl_check_fd(const void *data, struct file *f, unsigned int fd)
{
const struct dentry *dentry = data;
if (file_inode(f) == d_inode(dentry))
pr_warn_ratelimited("overlayfs: Warning: Copying up %pD, but open R/O on fd %u which will cease to be coherent [pid=%d %s]\n",
f, fd, current->pid, current->comm);
return 0;
}
/*
* Check the fds open by this process and warn if something like the following
* scenario is about to occur:
*
* fd1 = open("foo", O_RDONLY);
* fd2 = open("foo", O_RDWR);
*/
static void ovl_do_check_copy_up(struct dentry *dentry)
{
if (ovl_check_copy_up)
iterate_fd(current->files, 0, ovl_check_fd, dentry);
}
int ovl_copy_xattr(struct dentry *old, struct dentry *new)
{
ssize_t list_size, size, value_size = 0;
char *buf, *name, *value = NULL;
int uninitialized_var(error);
size_t slen;
if (!(old->d_inode->i_opflags & IOP_XATTR) ||
!(new->d_inode->i_opflags & IOP_XATTR))
return 0;
list_size = vfs_listxattr(old, NULL, 0);
if (list_size <= 0) {
if (list_size == -EOPNOTSUPP)
return 0;
return list_size;
}
buf = kzalloc(list_size, GFP_KERNEL);
if (!buf)
return -ENOMEM;
list_size = vfs_listxattr(old, buf, list_size);
if (list_size <= 0) {
error = list_size;
goto out;
}
for (name = buf; list_size; name += slen) {
slen = strnlen(name, list_size) + 1;
/* underlying fs providing us with an broken xattr list? */
if (WARN_ON(slen > list_size)) {
error = -EIO;
break;
}
list_size -= slen;
if (ovl_is_private_xattr(name))
continue;
retry:
size = vfs_getxattr(old, name, value, value_size);
if (size == -ERANGE)
size = vfs_getxattr(old, name, NULL, 0);
if (size < 0) {
error = size;
break;
}
if (size > value_size) {
void *new;
new = krealloc(value, size, GFP_KERNEL);
if (!new) {
error = -ENOMEM;
break;
}
value = new;
value_size = size;
goto retry;
}
error = security_inode_copy_up_xattr(name);
if (error < 0 && error != -EOPNOTSUPP)
break;
if (error == 1) {
error = 0;
continue; /* Discard */
}
error = vfs_setxattr(new, name, value, size, 0);
if (error)
break;
}
kfree(value);
out:
kfree(buf);
return error;
}
static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
{
struct file *old_file;
struct file *new_file;
loff_t old_pos = 0;
loff_t new_pos = 0;
int error = 0;
if (len == 0)
return 0;
old_file = ovl_path_open(old, O_LARGEFILE | O_RDONLY);
if (IS_ERR(old_file))
return PTR_ERR(old_file);
new_file = ovl_path_open(new, O_LARGEFILE | O_WRONLY);
if (IS_ERR(new_file)) {
error = PTR_ERR(new_file);
goto out_fput;
}
/* Try to use clone_file_range to clone up within the same fs */
error = vfs_clone_file_range(old_file, 0, new_file, 0, len);
if (!error)
goto out;
/* Couldn't clone, so now we try to copy the data */
error = 0;
/* FIXME: copy up sparse files efficiently */
while (len) {
size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
long bytes;
if (len < this_len)
this_len = len;
if (signal_pending_state(TASK_KILLABLE, current)) {
error = -EINTR;
break;
}
bytes = do_splice_direct(old_file, &old_pos