---
layout: "docs"
page_title: "Policies"
sidebar_current: "docs-concepts-policies"
description: |-
  Policies are how authorization is done in Vault, allowing you to restrict which parts of Vault a user can access.
---

# Access Control Policies

After [authenticating](/docs/concepts/auth.html) with Vault, the
next step is authorization. This is the process of determining what
a user is allowed to do. Authorization is unified in Vault in the form
of _policies_.

Policies are [HCL](https://github.com/hashicorp/hcl) or JSON documents
that describe what parts of Vault a user is allowed to access. An example
of a policy is shown below:

```javascript
path "sys/*" {
  policy = "deny"
}

path "secret/*" {
  policy = "write"
}

path "secret/foo" {
  policy = "read"
  capabilities = ["create", "sudo"]
}

path "secret/super-secret" {
  capabilities = ["deny"]
}
```

Policies use path based matching to apply rules. A policy may be an exact
match, or might be a glob pattern which uses a prefix. Vault operates in a
whitelisting mode, so if a path isn't explicitly allowed, Vault will reject
access to it.  This works well due to Vault's architecture of being like a
filesystem: everything has a path associated with it, including the core
configuration mechanism under "sys".

~> Policy paths are matched using the most specific defined policy. This may
be an exact match or the longest-prefix match of a glob. This means if you
define a policy for `"secret/foo*"`, the policy would also match `"secret/foobar"`.
The glob character is only supported at the end of the path specification.

## Capabilities and Policies

Paths have an associated set of capabilities that provide fine-grained control
over operations. The capabilities are:

  * `create` - Create a value at a path. (At present, few parts of Vault
    distinguish between `create` and `update`, so most operations require
    `update`. Parts of Vault that provide such a distinction, such as
    the `generic` backend, are noted in documentation.)

  * `read` - Read the value at a path.

  * `update` - Change the value at a path. In most parts of Vault, this also
    includes the ability to create the initial value at the path.

  * `delete` - Delete the value at a path.

  * `list` - List values at a path. Note that the keys returned by a `list`
    operation are *not* filtered by policies. You should not store
    sensitive/secret values in keys.

  * `sudo` - Gain access to paths that are _root-protected_. This is _additive_
    to other capabilities, so a path that requires `sudo` access will also
    require `read`, `update`, etc. as appropriate.

  * `deny` - No access allowed. This always takes precedence regardless of any
    other defined capabilities, including `sudo`.

The only non-obvious capability is `sudo`. Some routes within Vault and mounted
backends are marked as _root-protected_ paths. Clients aren't allowed to access
root paths unless they are a root user (have the special policy "root" attached
to their token) or have access to that path with the `sudo` capability (in
addition to the other necessary capabilities for performing an operation
against that path, such as `read` or `delete`).

For example, modifying the audit log backends is done via root paths.
Only root or `sudo` privilege users are allowed to do this.

Prior to Vault 0.5, the `policy` keyword was used per path rather than a set of
`capabilities`. In Vault 0.5+ these are still supported as shorthand and to
maintain backwards compatibility, but internally they map to a set of
capabilities. These mappings are as follows:

  * `deny` - `["deny"]`

  * `sudo` - `["create", "read", "update", "delete", "list", "sudo"]`

  * `write` - `["create", "read", "update", "delete", "list"]`

  * `read` - `["read", "list"]`

## Root Policy

The "root" policy is a special policy that can not be modified or removed.
Any user associated with the "root" policy becomes a root user. A root
user can do _anything_ within Vault.

There always exists at least one root user (associated with the token
when initializing a new server). After this root user, it is recommended
to create more strictly controlled users. The original root token should
be protected accordingly.

## Managing Policies

Policy management can be done via the API or CLI. The CLI commands are
`vault policies` and `vault policy-write`. Please see the help associated
with these commands for more information. They are very easy to use.

## Associating Policies

To associate a policy with a user, you must consult the documentation for
the authentication backend you're using.

For tokens, they are associated at creation time with `vault token-create`
and the `-policy` flags. Child tokens can be associated with a subset of
a parent's policies. Root users can assign any policies.

There is no way to modify the policies associated with an active
identity. The identity must be revoked and reauthenticated to receive
the new policy list.

If an _existing_ policy is modified, the modifications propagate
to all associated users instantly. The above paragraph is more specifically
stating that you can't add new or remove policies associated with an
active identity.

## Changes from 0.1

In Vault versions prior to 0.2, the ACL policy language had a slightly
different specification and semantics. The current specification requires
that glob behavior explicitly be specified by adding the `*` character to
the end of a path. Previously, all paths were glob based matches and no
exact match could be specified.

The other change is that deny had the lowest precedence. This meant if there
were two policies being merged (e.g. "ops" and "prod") and they had a conflicting
policy like:

```
path "sys/seal" {
    policy = "deny"
}

path "sys/seal" {
    policy = "read"
}
```

The merge would previously give the "read" higher precedence. The current
version of Vault prioritizes the explicit deny, so that the "deny" would
take precedence.

To make all Vault 0.1 policies compatible with Vault 0.2+, the explicit
glob character must be added to all the path prefixes.