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![Amir Goldstein](/assets/img/avatar_default.png)
Most overlayfs c files already explicitly include ovl_entry.h to use overlay entry struct definitions and upcoming changes are going to require even more c files to include this header. All overlayfs c files include overlayfs.h and overlayfs.h itself refers to some structs defined in ovl_entry.h, so it seems more logic to include ovl_entry.h from overlayfs.h than from c files. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
702 lines
16 KiB
C
702 lines
16 KiB
C
/*
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*
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* Copyright (C) 2011 Novell Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/slab.h>
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#include <linux/file.h>
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#include <linux/splice.h>
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#include <linux/xattr.h>
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#include <linux/security.h>
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#include <linux/uaccess.h>
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#include <linux/sched/signal.h>
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#include <linux/cred.h>
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#include <linux/namei.h>
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#include <linux/fdtable.h>
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#include <linux/ratelimit.h>
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#include <linux/exportfs.h>
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#include "overlayfs.h"
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#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
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static bool __read_mostly ovl_check_copy_up;
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module_param_named(check_copy_up, ovl_check_copy_up, bool,
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S_IWUSR | S_IRUGO);
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MODULE_PARM_DESC(ovl_check_copy_up,
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"Warn on copy-up when causing process also has a R/O fd open");
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static int ovl_check_fd(const void *data, struct file *f, unsigned int fd)
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{
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const struct dentry *dentry = data;
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if (file_inode(f) == d_inode(dentry))
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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",
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f, fd, current->pid, current->comm);
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return 0;
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}
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/*
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* Check the fds open by this process and warn if something like the following
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* scenario is about to occur:
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*
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* fd1 = open("foo", O_RDONLY);
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* fd2 = open("foo", O_RDWR);
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*/
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static void ovl_do_check_copy_up(struct dentry *dentry)
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{
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if (ovl_check_copy_up)
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iterate_fd(current->files, 0, ovl_check_fd, dentry);
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}
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int ovl_copy_xattr(struct dentry *old, struct dentry *new)
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{
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ssize_t list_size, size, value_size = 0;
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char *buf, *name, *value = NULL;
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int uninitialized_var(error);
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size_t slen;
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if (!(old->d_inode->i_opflags & IOP_XATTR) ||
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!(new->d_inode->i_opflags & IOP_XATTR))
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return 0;
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list_size = vfs_listxattr(old, NULL, 0);
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if (list_size <= 0) {
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if (list_size == -EOPNOTSUPP)
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return 0;
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return list_size;
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}
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buf = kzalloc(list_size, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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list_size = vfs_listxattr(old, buf, list_size);
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if (list_size <= 0) {
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error = list_size;
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goto out;
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}
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for (name = buf; list_size; name += slen) {
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slen = strnlen(name, list_size) + 1;
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/* underlying fs providing us with an broken xattr list? */
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if (WARN_ON(slen > list_size)) {
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error = -EIO;
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break;
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}
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list_size -= slen;
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if (ovl_is_private_xattr(name))
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continue;
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retry:
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size = vfs_getxattr(old, name, value, value_size);
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if (size == -ERANGE)
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size = vfs_getxattr(old, name, NULL, 0);
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if (size < 0) {
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error = size;
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break;
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}
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if (size > value_size) {
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void *new;
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new = krealloc(value, size, GFP_KERNEL);
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if (!new) {
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error = -ENOMEM;
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break;
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}
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value = new;
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value_size = size;
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goto retry;
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}
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error = security_inode_copy_up_xattr(name);
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if (error < 0 && error != -EOPNOTSUPP)
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break;
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if (error == 1) {
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error = 0;
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continue; /* Discard */
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}
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error = vfs_setxattr(new, name, value, size, 0);
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if (error)
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break;
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}
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kfree(value);
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out:
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kfree(buf);
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return error;
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}
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static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
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{
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struct file *old_file;
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struct file *new_file;
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loff_t old_pos = 0;
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loff_t new_pos = 0;
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int error = 0;
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if (len == 0)
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return 0;
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old_file = ovl_path_open(old, O_LARGEFILE | O_RDONLY);
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if (IS_ERR(old_file))
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return PTR_ERR(old_file);
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new_file = ovl_path_open(new, O_LARGEFILE | O_WRONLY);
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if (IS_ERR(new_file)) {
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error = PTR_ERR(new_file);
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goto out_fput;
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}
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/* Try to use clone_file_range to clone up within the same fs */
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error = vfs_clone_file_range(old_file, 0, new_file, 0, len);
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if (!error)
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goto out;
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/* Couldn't clone, so now we try to copy the data */
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error = 0;
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/* FIXME: copy up sparse files efficiently */
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while (len) {
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size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
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long bytes;
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if (len < this_len)
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this_len = len;
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if (signal_pending_state(TASK_KILLABLE, current)) {
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error = -EINTR;
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break;
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}
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bytes = do_splice_direct(old_file, &old_pos,
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new_file, &new_pos,
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this_len, SPLICE_F_MOVE);
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if (bytes <= 0) {
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error = bytes;
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break;
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}
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WARN_ON(old_pos != new_pos);
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len -= bytes;
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}
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out:
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if (!error)
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error = vfs_fsync(new_file, 0);
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fput(new_file);
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out_fput:
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fput(old_file);
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return error;
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}
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static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
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{
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struct iattr attr = {
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.ia_valid =
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ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET,
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.ia_atime = stat->atime,
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.ia_mtime = stat->mtime,
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};
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return notify_change(upperdentry, &attr, NULL);
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}
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int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
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{
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int err = 0;
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if (!S_ISLNK(stat->mode)) {
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struct iattr attr = {
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.ia_valid = ATTR_MODE,
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.ia_mode = stat->mode,
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};
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err = notify_change(upperdentry, &attr, NULL);
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}
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if (!err) {
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struct iattr attr = {
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.ia_valid = ATTR_UID | ATTR_GID,
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.ia_uid = stat->uid,
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.ia_gid = stat->gid,
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};
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err = notify_change(upperdentry, &attr, NULL);
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}
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if (!err)
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ovl_set_timestamps(upperdentry, stat);
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return err;
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}
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struct ovl_fh *ovl_encode_fh(struct dentry *lower, bool is_upper)
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{
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struct ovl_fh *fh;
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int fh_type, fh_len, dwords;
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void *buf;
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int buflen = MAX_HANDLE_SZ;
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uuid_t *uuid = &lower->d_sb->s_uuid;
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buf = kmalloc(buflen, GFP_KERNEL);
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if (!buf)
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return ERR_PTR(-ENOMEM);
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/*
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* We encode a non-connectable file handle for non-dir, because we
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* only need to find the lower inode number and we don't want to pay
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* the price or reconnecting the dentry.
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*/
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dwords = buflen >> 2;
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fh_type = exportfs_encode_fh(lower, buf, &dwords, 0);
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buflen = (dwords << 2);
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fh = ERR_PTR(-EIO);
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if (WARN_ON(fh_type < 0) ||
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WARN_ON(buflen > MAX_HANDLE_SZ) ||
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WARN_ON(fh_type == FILEID_INVALID))
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goto out;
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BUILD_BUG_ON(MAX_HANDLE_SZ + offsetof(struct ovl_fh, fid) > 255);
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fh_len = offsetof(struct ovl_fh, fid) + buflen;
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fh = kmalloc(fh_len, GFP_KERNEL);
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if (!fh) {
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fh = ERR_PTR(-ENOMEM);
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goto out;
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}
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fh->version = OVL_FH_VERSION;
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fh->magic = OVL_FH_MAGIC;
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fh->type = fh_type;
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fh->flags = OVL_FH_FLAG_CPU_ENDIAN;
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/*
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* When we will want to decode an overlay dentry from this handle
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* and all layers are on the same fs, if we get a disconncted real
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* dentry when we decode fid, the only way to tell if we should assign
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* it to upperdentry or to lowerstack is by checking this flag.
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*/
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if (is_upper)
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fh->flags |= OVL_FH_FLAG_PATH_UPPER;
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fh->len = fh_len;
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fh->uuid = *uuid;
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memcpy(fh->fid, buf, buflen);
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out:
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kfree(buf);
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return fh;
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}
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static int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
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struct dentry *upper)
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{
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const struct ovl_fh *fh = NULL;
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int err;
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/*
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* When lower layer doesn't support export operations store a 'null' fh,
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* so we can use the overlay.origin xattr to distignuish between a copy
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* up and a pure upper inode.
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*/
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if (ovl_can_decode_fh(lower->d_sb)) {
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fh = ovl_encode_fh(lower, false);
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if (IS_ERR(fh))
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return PTR_ERR(fh);
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}
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/*
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* Do not fail when upper doesn't support xattrs.
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*/
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err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh,
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fh ? fh->len : 0, 0);
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kfree(fh);
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return err;
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}
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struct ovl_copy_up_ctx {
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struct dentry *parent;
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struct dentry *dentry;
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struct path lowerpath;
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struct kstat stat;
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struct kstat pstat;
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const char *link;
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struct dentry *destdir;
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struct qstr destname;
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struct dentry *workdir;
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bool tmpfile;
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bool origin;
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};
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static int ovl_link_up(struct ovl_copy_up_ctx *c)
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{
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int err;
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struct dentry *upper;
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struct dentry *upperdir = ovl_dentry_upper(c->parent);
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struct inode *udir = d_inode(upperdir);
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/* Mark parent "impure" because it may now contain non-pure upper */
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err = ovl_set_impure(c->parent, upperdir);
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if (err)
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return err;
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err = ovl_set_nlink_lower(c->dentry);
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if (err)
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return err;
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inode_lock_nested(udir, I_MUTEX_PARENT);
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upper = lookup_one_len(c->dentry->d_name.name, upperdir,
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c->dentry->d_name.len);
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err = PTR_ERR(upper);
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if (!IS_ERR(upper)) {
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err = ovl_do_link(ovl_dentry_upper(c->dentry), udir, upper,
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true);
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dput(upper);
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if (!err) {
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/* Restore timestamps on parent (best effort) */
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ovl_set_timestamps(upperdir, &c->pstat);
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ovl_dentry_set_upper_alias(c->dentry);
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}
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}
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inode_unlock(udir);
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ovl_set_nlink_upper(c->dentry);
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return err;
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}
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static int ovl_install_temp(struct ovl_copy_up_ctx *c, struct dentry *temp,
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struct dentry **newdentry)
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{
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int err;
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struct dentry *upper;
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struct inode *udir = d_inode(c->destdir);
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upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
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if (IS_ERR(upper))
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return PTR_ERR(upper);
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if (c->tmpfile)
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err = ovl_do_link(temp, udir, upper, true);
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else
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err = ovl_do_rename(d_inode(c->workdir), temp, udir, upper, 0);
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if (!err)
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*newdentry = dget(c->tmpfile ? upper : temp);
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dput(upper);
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return err;
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}
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static int ovl_get_tmpfile(struct ovl_copy_up_ctx *c, struct dentry **tempp)
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{
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int err;
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struct dentry *temp;
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const struct cred *old_creds = NULL;
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struct cred *new_creds = NULL;
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struct cattr cattr = {
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/* Can't properly set mode on creation because of the umask */
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.mode = c->stat.mode & S_IFMT,
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.rdev = c->stat.rdev,
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.link = c->link
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};
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err = security_inode_copy_up(c->dentry, &new_creds);
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if (err < 0)
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goto out;
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if (new_creds)
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old_creds = override_creds(new_creds);
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if (c->tmpfile) {
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temp = ovl_do_tmpfile(c->workdir, c->stat.mode);
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if (IS_ERR(temp))
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goto temp_err;
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} else {
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temp = ovl_lookup_temp(c->workdir);
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if (IS_ERR(temp))
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goto temp_err;
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err = ovl_create_real(d_inode(c->workdir), temp, &cattr,
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NULL, true);
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if (err) {
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dput(temp);
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goto out;
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}
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}
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err = 0;
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*tempp = temp;
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out:
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if (new_creds) {
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revert_creds(old_creds);
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put_cred(new_creds);
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}
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return err;
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temp_err:
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err = PTR_ERR(temp);
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goto out;
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}
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static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
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{
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int err;
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if (S_ISREG(c->stat.mode)) {
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struct path upperpath;
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ovl_path_upper(c->dentry, &upperpath);
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BUG_ON(upperpath.dentry != NULL);
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upperpath.dentry = temp;
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err = ovl_copy_up_data(&c->lowerpath, &upperpath, c->stat.size);
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if (err)
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return err;
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}
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err = ovl_copy_xattr(c->lowerpath.dentry, temp);
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if (err)
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return err;
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inode_lock(temp->d_inode);
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err = ovl_set_attr(temp, &c->stat);
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inode_unlock(temp->d_inode);
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if (err)
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return err;
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/*
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* Store identifier of lower inode in upper inode xattr to
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* allow lookup of the copy up origin inode.
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*
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* Don't set origin when we are breaking the association with a lower
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* hard link.
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*/
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if (c->origin) {
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err = ovl_set_origin(c->dentry, c->lowerpath.dentry, temp);
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if (err)
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return err;
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}
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return 0;
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}
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static int ovl_copy_up_locked(struct ovl_copy_up_ctx *c)
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{
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struct inode *udir = c->destdir->d_inode;
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struct inode *inode;
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struct dentry *newdentry = NULL;
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struct dentry *temp = NULL;
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int err;
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err = ovl_get_tmpfile(c, &temp);
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if (err)
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goto out;
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err = ovl_copy_up_inode(c, temp);
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if (err)
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goto out_cleanup;
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if (c->tmpfile) {
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inode_lock_nested(udir, I_MUTEX_PARENT);
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err = ovl_install_temp(c, temp, &newdentry);
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inode_unlock(udir);
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} else {
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err = ovl_install_temp(c, temp, &newdentry);
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}
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if (err)
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goto out_cleanup;
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inode = d_inode(c->dentry);
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ovl_inode_update(inode, newdentry);
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if (S_ISDIR(inode->i_mode))
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ovl_set_flag(OVL_WHITEOUTS, inode);
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out:
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dput(temp);
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return err;
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out_cleanup:
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if (!c->tmpfile)
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ovl_cleanup(d_inode(c->workdir), temp);
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goto out;
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}
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/*
|
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* Copy up a single dentry
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*
|
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* All renames start with copy up of source if necessary. The actual
|
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* rename will only proceed once the copy up was successful. Copy up uses
|
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* upper parent i_mutex for exclusion. Since rename can change d_parent it
|
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* is possible that the copy up will lock the old parent. At that point
|
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* the file will have already been copied up anyway.
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*/
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static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
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{
|
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int err;
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struct ovl_fs *ofs = c->dentry->d_sb->s_fs_info;
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bool indexed = false;
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|
|
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if (ovl_indexdir(c->dentry->d_sb) && !S_ISDIR(c->stat.mode) &&
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c->stat.nlink > 1)
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indexed = true;
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if (S_ISDIR(c->stat.mode) || c->stat.nlink == 1 || indexed)
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c->origin = true;
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if (indexed) {
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c->destdir = ovl_indexdir(c->dentry->d_sb);
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err = ovl_get_index_name(c->lowerpath.dentry, &c->destname);
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if (err)
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return err;
|
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} else {
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/*
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* Mark parent "impure" because it may now contain non-pure
|
|
* upper
|
|
*/
|
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err = ovl_set_impure(c->parent, c->destdir);
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if (err)
|
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return err;
|
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}
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|
|
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/* Should we copyup with O_TMPFILE or with workdir? */
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if (S_ISREG(c->stat.mode) && ofs->tmpfile) {
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c->tmpfile = true;
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err = ovl_copy_up_locked(c);
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} else {
|
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err = ovl_lock_rename_workdir(c->workdir, c->destdir);
|
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if (!err) {
|
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err = ovl_copy_up_locked(c);
|
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unlock_rename(c->workdir, c->destdir);
|
|
}
|
|
}
|
|
|
|
if (indexed) {
|
|
if (!err)
|
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ovl_set_flag(OVL_INDEX, d_inode(c->dentry));
|
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kfree(c->destname.name);
|
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} else if (!err) {
|
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struct inode *udir = d_inode(c->destdir);
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|
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/* Restore timestamps on parent (best effort) */
|
|
inode_lock(udir);
|
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ovl_set_timestamps(c->destdir, &c->pstat);
|
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inode_unlock(udir);
|
|
|
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ovl_dentry_set_upper_alias(c->dentry);
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
|
|
int flags)
|
|
{
|
|
int err;
|
|
DEFINE_DELAYED_CALL(done);
|
|
struct path parentpath;
|
|
struct ovl_copy_up_ctx ctx = {
|
|
.parent = parent,
|
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.dentry = dentry,
|
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.workdir = ovl_workdir(dentry),
|
|
};
|
|
|
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if (WARN_ON(!ctx.workdir))
|
|
return -EROFS;
|
|
|
|
ovl_path_lower(dentry, &ctx.lowerpath);
|
|
err = vfs_getattr(&ctx.lowerpath, &ctx.stat,
|
|
STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
|
|
if (err)
|
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return err;
|
|
|
|
ovl_path_upper(parent, &parentpath);
|
|
ctx.destdir = parentpath.dentry;
|
|
ctx.destname = dentry->d_name;
|
|
|
|
err = vfs_getattr(&parentpath, &ctx.pstat,
|
|
STATX_ATIME | STATX_MTIME, AT_STATX_SYNC_AS_STAT);
|
|
if (err)
|
|
return err;
|
|
|
|
/* maybe truncate regular file. this has no effect on dirs */
|
|
if (flags & O_TRUNC)
|
|
ctx.stat.size = 0;
|
|
|
|
if (S_ISLNK(ctx.stat.mode)) {
|
|
ctx.link = vfs_get_link(ctx.lowerpath.dentry, &done);
|
|
if (IS_ERR(ctx.link))
|
|
return PTR_ERR(ctx.link);
|
|
}
|
|
ovl_do_check_copy_up(ctx.lowerpath.dentry);
|
|
|
|
err = ovl_copy_up_start(dentry);
|
|
/* err < 0: interrupted, err > 0: raced with another copy-up */
|
|
if (unlikely(err)) {
|
|
if (err > 0)
|
|
err = 0;
|
|
} else {
|
|
if (!ovl_dentry_upper(dentry))
|
|
err = ovl_do_copy_up(&ctx);
|
|
if (!err && !ovl_dentry_has_upper_alias(dentry))
|
|
err = ovl_link_up(&ctx);
|
|
ovl_copy_up_end(dentry);
|
|
}
|
|
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;
|
|
|
|
/*
|
|
* Check if copy-up has happened as well as for upper alias (in
|
|
* case of hard links) is there.
|
|
*
|
|
* Both checks are lockless:
|
|
* - false negatives: will recheck under oi->lock
|
|
* - false positives:
|
|
* + ovl_dentry_upper() uses memory barriers to ensure the
|
|
* upper dentry is up-to-date
|
|
* + ovl_dentry_has_upper_alias() relies on locking of
|
|
* upper parent i_rwsem to prevent reordering copy-up
|
|
* with rename.
|
|
*/
|
|
if (ovl_dentry_upper(dentry) &&
|
|
ovl_dentry_has_upper_alias(dentry))
|
|
break;
|
|
|
|
next = dget(dentry);
|
|
/* find the topmost dentry not yet copied up */
|
|
for (;;) {
|
|
parent = dget_parent(next);
|
|
|
|
if (ovl_dentry_upper(parent))
|
|
break;
|
|
|
|
dput(next);
|
|
next = parent;
|
|
}
|
|
|
|
err = ovl_copy_up_one(parent, next, flags);
|
|
|
|
dput(parent);
|
|
dput(next);
|
|
}
|
|
revert_creds(old_cred);
|
|
|
|
return err;
|
|
}
|
|
|
|
int ovl_copy_up(struct dentry *dentry)
|
|
{
|
|
return ovl_copy_up_flags(dentry, 0);
|
|
}
|