blob: e8cacf7a8dccd9ff1dafe3f3a0371367ad267ba6 [file] [log] [blame]
/*
*
* 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.h>
#include <linux/namei.h>
#include <linux/fdtable.h>
#include <linux/ratelimit.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 (f->f_inode == 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,
new_file, &new_pos,
this_len, SPLICE_F_MOVE);
if (bytes <= 0) {
error = bytes;
break;
}
WARN_ON(old_pos != new_pos);
len -= bytes;
}
out:
if (!error)
error = vfs_fsync(new_file, 0);
fput(new_file);
out_fput:
fput(old_file);
return error;
}
static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
{
struct iattr attr = {
.ia_valid =
ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET,
.ia_atime = stat->atime,
.ia_mtime = stat->mtime,
};
return notify_change(upperdentry, &attr, NULL);
}
int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
{
int err = 0;
if (!S_ISLNK(stat->mode)) {
struct iattr attr = {
.ia_valid = ATTR_MODE,
.ia_mode = stat->mode,
};
err = notify_change(upperdentry, &attr, NULL);
}
if (!err) {
struct iattr attr = {
.ia_valid = ATTR_UID | ATTR_GID,
.ia_uid = stat->uid,
.ia_gid = stat->gid,
};
err = notify_change(upperdentry, &attr, NULL);
}
if (!err)
ovl_set_timestamps(upperdentry, stat);
return err;
}
static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
struct dentry *dentry, struct path *lowerpath,
struct kstat *stat, const char *link)
{
struct inode *wdir = workdir->d_inode;
struct inode *udir = upperdir->d_inode;
struct dentry *newdentry = NULL;
struct dentry *upper = NULL;
umode_t mode = stat->mode;
int err;
const struct cred *old_creds = NULL;
struct cred *new_creds = NULL;
newdentry = ovl_lookup_temp(workdir, dentry);
err = PTR_ERR(newdentry);
if (IS_ERR(newdentry))
goto out;
upper = lookup_one_len(dentry->d_name.name, upperdir,
dentry->d_name.len);
err = PTR_ERR(upper);
if (IS_ERR(upper))
goto out1;
err = security_inode_copy_up(dentry, &new_creds);
if (err < 0)
goto out2;
if (new_creds)
old_creds = override_creds(new_creds);
/* Can't properly set mode on creation because of the umask */
stat->mode &= S_IFMT;
err = ovl_create_real(wdir, newdentry, stat, link, NULL, true);
stat->mode = mode;
if (new_creds) {
revert_creds(old_creds);
put_cred(new_creds);
}
if (err)
goto out2;
if (S_ISREG(stat->mode)) {
struct path upperpath;
ovl_path_upper(dentry, &upperpath);
BUG_ON(upperpath.dentry != NULL);
upperpath.dentry = newdentry;
err = ovl_copy_up_data(lowerpath, &upperpath, stat->size);
if (err)
goto out_cleanup;
}
err = ovl_copy_xattr(lowerpath->dentry, newdentry);
if (err)
goto out_cleanup;
inode_lock(newdentry->d_inode);
err = ovl_set_attr(newdentry, stat);
inode_unlock(newdentry->d_inode);
if (err)
goto out_cleanup;
err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
if (err)
goto out_cleanup;
ovl_dentry_update(dentry, newdentry);
ovl_inode_update(d_inode(dentry), d_inode(newdentry));
newdentry = NULL;
out2:
dput(upper);
out1:
dput(newdentry);
out:
return err;
out_cleanup:
ovl_cleanup(wdir, newdentry);
goto out2;
}
/*
* Copy up a single dentry
*
* All renames start with copy up of source if necessary. The actual
* rename will only proceed once the copy up was successful. Copy up uses
* upper parent i_mutex for exclusion. Since rename can change d_parent it
* is possible that the copy up will lock the old parent. At that point
* the file will have already been copied up anyway.
*/
static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
struct path *lowerpath, struct kstat *stat)
{
DEFINE_DELAYED_CALL(done);
struct dentry *workdir = ovl_workdir(dentry);
int err;
struct kstat pstat;
struct path parentpath;
struct dentry *lowerdentry = lowerpath->dentry;
struct dentry *upperdir;
const char *link = NULL;
if (WARN_ON(!workdir))
return -EROFS;
ovl_do_check_copy_up(lowerdentry);
ovl_path_upper(parent, &parentpath);
upperdir = parentpath.dentry;
err = vfs_getattr(&parentpath, &pstat);
if (err)
return err;
if (S_ISLNK(stat->mode)) {
link = vfs_get_link(lowerdentry, &done);
if (IS_ERR(link))
return PTR_ERR(link);
}
err = -EIO;
if (lock_rename(workdir, upperdir) != NULL) {
pr_err("overlayfs: failed to lock workdir+upperdir\n");
goto out_unlock;
}
if (ovl_dentry_upper(dentry)) {
/* Raced with another copy-up? Nothing to do, then... */
err = 0;
goto out_unlock;
}
err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,
stat, link);
if (!err) {
/* Restore timestamps on parent (best effort) */
ovl_set_timestamps(upperdir, &pstat);
}
out_unlock:
unlock_rename(workdir, upperdir);
do_delayed_call(&done);
return err;
}
int ovl_copy_up_flags(struct dentry *dentry, int flags)
{
int err = 0;
const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
while (!err) {
struct dentry *next;
struct dentry *parent;
struct path lowerpath;
struct kstat stat;
enum ovl_path_type type = ovl_path_type(dentry);
if (OVL_TYPE_UPPER(type))
break;
next = dget(dentry);
/* find the topmost dentry not yet copied up */
for (;;) {
parent = dget_parent(next);
type = ovl_path_type(parent);
if (OVL_TYPE_UPPER(type))
break;
dput(next);
next = parent;
}
ovl_path_lower(next, &lowerpath);
err = vfs_getattr(&lowerpath, &stat);
/* maybe truncate regular file. this has no effect on dirs */
if (flags & O_TRUNC)
stat.size = 0;
if (!err)
err = ovl_copy_up_one(parent, next, &lowerpath, &stat);
dput(parent);
dput(next);
}
revert_creds(old_cred);
return err;
}
int ovl_copy_up(struct dentry *dentry)
{
return ovl_copy_up_flags(dentry, 0);
}