path: root/fs/overlayfs/copy_up.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 * Copyright (C) 2011 Novell Inc.
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/fileattr.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 int ovl_ccup_set(const char *buf, const struct kernel_param *param)
{
	pr_warn("\"check_copy_up\" module option is obsolete\n");
	return 0;
}

static int ovl_ccup_get(char *buf, const struct kernel_param *param)
{
	return sprintf(buf, "N\n");
}

module_param_call(check_copy_up, ovl_ccup_set, ovl_ccup_get, NULL, 0644);
MODULE_PARM_DESC(check_copy_up, "Obsolete; does nothing");

static bool ovl_must_copy_xattr(const char *name)
{
	return !strcmp(name, XATTR_POSIX_ACL_ACCESS) ||
	       !strcmp(name, XATTR_POSIX_ACL_DEFAULT) ||
	       !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN);
}

int ovl_copy_xattr(struct super_block *sb, struct dentry *old,
		   struct dentry *new)
{
	ssize_t list_size, size, value_size = 0;
	char *buf, *name, *value = NULL;
	int error = 0;
	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 = kvzalloc(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(sb, name))
			continue;

		error = security_inode_copy_up_xattr(name);
		if (error < 0 && error != -EOPNOTSUPP)
			break;
		if (error == 1) {
			error = 0;
			continue; /* Discard */
		}
retry:
		size = vfs_getxattr(&init_user_ns, old, name, value, value_size);
		if (size == -ERANGE)
			size = vfs_getxattr(&init_user_ns, old, name, NULL, 0);

		if (size < 0) {
			error = size;
			break;
		}

		if (size > value_size) {
			void *new;

			new = kvmalloc(size, GFP_KERNEL);
			if (!new) {
				error = -ENOMEM;
				break;
			}
			kvfree(value);
			value = new;
			value_size = size;
			goto retry;
		}

		error = vfs_setxattr(&init_user_ns, new, name, value, size, 0);
		if (error) {
			if (error != -EOPNOTSUPP || ovl_must_copy_xattr(name))
				break;

			/* Ignore failure to copy unknown xattrs */
			error = 0;
		}
	}
	kvfree(value);
out:
	kvfree(buf);
	return error;
}

static int ovl_copy_fileattr(struct inode *inode, struct path *old,
			     struct path *new)
{
	struct fileattr oldfa = { .flags_valid = true };
	struct fileattr newfa = { .flags_valid = true };
	int err;

	err = ovl_real_fileattr_get(old, &oldfa);
	if (err) {
		/* Ntfs-3g returns -EINVAL for "no fileattr support" */
		if (err == -ENOTTY || err == -EINVAL)
			return 0;
		pr_warn("failed to retrieve lower fileattr (%pd2, err=%i)\n",
			old, err);
		return err;
	}

	/*
	 * We cannot set immutable and append-only flags on upper inode,
	 * because we would not be able to link upper inode to upper dir
	 * not set overlay private xattr on upper inode.
	 * Store these flags in overlay.protattr xattr instead.
	 */
	if (oldfa.flags & OVL_PROT_FS_FLAGS_MASK) {
		err = ovl_set_protattr(inode, new->dentry, &oldfa);
		if (err)
			return err;</