1/*
  2 * FUSE: Filesystem in Userspace
  3 * Copyright (C) 2016 Canonical Ltd. <seth.forshee@canonical.com>
  4 *
  5 * This program can be distributed under the terms of the GNU GPL.
  6 * See the file COPYING.
  7 */
  8
  9#include "fuse_i.h"
 10
 11#include <linux/posix_acl.h>
 12#include <linux/posix_acl_xattr.h>
 13
 14struct posix_acl *fuse_get_acl(struct inode *inode, int type)
 15{
 16	struct fuse_conn *fc = get_fuse_conn(inode);
 17	int size;
 18	const char *name;
 19	void *value = NULL;
 20	struct posix_acl *acl;
 21
 22	if (fuse_is_bad(inode))
 23		return ERR_PTR(-EIO);
 24
 25	if (!fc->posix_acl || fc->no_getxattr)
 26		return NULL;
 27
 28	if (type == ACL_TYPE_ACCESS)
 29		name = XATTR_NAME_POSIX_ACL_ACCESS;
 30	else if (type == ACL_TYPE_DEFAULT)
 31		name = XATTR_NAME_POSIX_ACL_DEFAULT;
 32	else
 33		return ERR_PTR(-EOPNOTSUPP);
 34
 35	value = kmalloc(PAGE_SIZE, GFP_KERNEL);
 36	if (!value)
 37		return ERR_PTR(-ENOMEM);
 38	size = fuse_getxattr(inode, name, value, PAGE_SIZE);
 39	if (size > 0)
 40		acl = posix_acl_from_xattr(fc->user_ns, value, size);
 41	else if ((size == 0) || (size == -ENODATA) ||
 42		 (size == -EOPNOTSUPP && fc->no_getxattr))
 43		acl = NULL;
 44	else if (size == -ERANGE)
 45		acl = ERR_PTR(-E2BIG);
 46	else
 47		acl = ERR_PTR(size);
 48
 49	kfree(value);
 50	return acl;
 51}
 52
 53int fuse_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
 54		 struct posix_acl *acl, int type)
 55{
 56	struct fuse_conn *fc = get_fuse_conn(inode);
 57	const char *name;
 58	int ret;
 59
 60	if (fuse_is_bad(inode))
 61		return -EIO;
 62
 63	if (!fc->posix_acl || fc->no_setxattr)
 64		return -EOPNOTSUPP;
 65
 66	if (type == ACL_TYPE_ACCESS)
 67		name = XATTR_NAME_POSIX_ACL_ACCESS;
 68	else if (type == ACL_TYPE_DEFAULT)
 69		name = XATTR_NAME_POSIX_ACL_DEFAULT;
 70	else
 71		return -EINVAL;
 72
 73	if (acl) {
 74		unsigned int extra_flags = 0;
 75		/*
 76		 * Fuse userspace is responsible for updating access
 77		 * permissions in the inode, if needed. fuse_setxattr
 78		 * invalidates the inode attributes, which will force
 79		 * them to be refreshed the next time they are used,
 80		 * and it also updates i_ctime.
 81		 */
 82		size_t size = posix_acl_xattr_size(acl->a_count);
 83		void *value;
 84
 85		if (size > PAGE_SIZE)
 86			return -E2BIG;
 87
 88		value = kmalloc(size, GFP_KERNEL);
 89		if (!value)
 90			return -ENOMEM;
 91
 92		ret = posix_acl_to_xattr(fc->user_ns, acl, value, size);
 93		if (ret < 0) {
 94			kfree(value);
 95			return ret;
 96		}
 97
 98		if (!in_group_p(i_gid_into_mnt(&init_user_ns, inode)) &&
 99		    !capable_wrt_inode_uidgid(&init_user_ns, inode, CAP_FSETID))
100			extra_flags |= FUSE_SETXATTR_ACL_KILL_SGID;
101
102		ret = fuse_setxattr(inode, name, value, size, 0, extra_flags);
103		kfree(value);
104	} else {
105		ret = fuse_removexattr(inode, name);
106	}
107	forget_all_cached_acls(inode);
108	fuse_invalidate_attr(inode);
109
110	return ret;
111}