mirror_zfs/include/os/linux/zfs/sys/policy.h
Matthew Ahrens e59a377a8f
filesystem_limit/snapshot_limit is incorrectly enforced against root
The filesystem_limit and snapshot_limit properties limit the number of
filesystems or snapshots that can be created below this dataset.
According to the manpage, "The limit is not enforced if the user is
allowed to change the limit."  Two types of users are allowed to change
the limit:

1. Those that have been delegated the `filesystem_limit` or
`snapshot_limit` permission, e.g. with
`zfs allow USER filesystem_limit DATASET`.  This works properly.

2. A user with elevated system privileges (e.g. root).  This does not
work - the root user will incorrectly get an error when trying to create
a snapshot/filesystem, if it exceeds the `_limit` property.

The problem is that `priv_policy_ns()` does not work if the `cred_t` is
not that of the current process.  This happens when
`dsl_enforce_ds_ss_limits()` is called in syncing context (as part of a
sync task's check func) to determine the permissions of the
corresponding user process.

This commit fixes the issue by passing the `task_struct` (typedef'ed as
a `proc_t`) to syncing context, and then using `has_capability()` to
determine if that process is privileged.  Note that we still need to
pass the `cred_t` to syncing context so that we can check if the user
was delegated this permission with `zfs allow`.

This problem only impacts Linux.  Wrappers are added to FreeBSD but it
continues to use `priv_check_cred()`, which works on arbitrary `cred_t`.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #8226
Closes #10545
2020-07-11 17:18:02 -07:00

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2.2 KiB
C

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
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* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
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* CDDL HEADER END
*/
/*
* Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright 2015, Joyent, Inc. All rights reserved.
* Copyright (c) 2016, Lawrence Livermore National Security, LLC.
*/
#ifndef _SYS_POLICY_H
#define _SYS_POLICY_H
#ifdef _KERNEL
#include <sys/cred.h>
#include <sys/types.h>
#include <sys/xvattr.h>
#include <sys/zpl.h>
int secpolicy_nfs(const cred_t *);
int secpolicy_sys_config(const cred_t *, boolean_t);
int secpolicy_vnode_access2(const cred_t *, struct inode *,
uid_t, mode_t, mode_t);
int secpolicy_vnode_any_access(const cred_t *, struct inode *, uid_t);
int secpolicy_vnode_chown(const cred_t *, uid_t);
int secpolicy_vnode_create_gid(const cred_t *);
int secpolicy_vnode_remove(const cred_t *);
int secpolicy_vnode_setdac(const cred_t *, uid_t);
int secpolicy_vnode_setid_retain(const cred_t *, boolean_t);
int secpolicy_vnode_setids_setgids(const cred_t *, gid_t);
int secpolicy_zinject(const cred_t *);
int secpolicy_zfs(const cred_t *);
int secpolicy_zfs_proc(const cred_t *, proc_t *);
void secpolicy_setid_clear(vattr_t *, cred_t *);
int secpolicy_setid_setsticky_clear(struct inode *, vattr_t *,
const vattr_t *, cred_t *);
int secpolicy_xvattr(xvattr_t *, uid_t, cred_t *, mode_t);
int secpolicy_vnode_setattr(cred_t *, struct inode *, struct vattr *,
const struct vattr *, int, int (void *, int, cred_t *), void *);
int secpolicy_basic_link(const cred_t *);
#endif /* _KERNEL */
#endif /* _SYS_POLICY_H */