147 lines
5.5 KiB
Plaintext
147 lines
5.5 KiB
Plaintext
---
|
|
layout: docs
|
|
page_title: TLS Certificates - Auth Methods
|
|
description: >-
|
|
The "cert" auth method allows users to authenticate with Vault using TLS
|
|
client certificates.
|
|
---
|
|
|
|
# TLS Certificates Auth Method
|
|
|
|
@include 'x509-sha1-deprecation.mdx'
|
|
|
|
The `cert` auth method allows authentication using SSL/TLS client certificates
|
|
which are either signed by a CA or self-signed. SSL/TLS client certificates
|
|
are defined as having an `ExtKeyUsage` extension with the usage set to either
|
|
`ClientAuth` or `Any`.
|
|
|
|
The trusted certificates and CAs are configured directly to the auth method
|
|
using the `certs/` path. This method cannot read trusted certificates from an
|
|
external source.
|
|
|
|
CA certificates are associated with a role; role names and CRL names are normalized to
|
|
lower-case.
|
|
|
|
Please note that to use this auth method, `tls_disable` must be false in the Vault
|
|
configuration. This is because the certificates are sent through TLS communication itself.
|
|
|
|
## Revocation Checking
|
|
|
|
Since Vault 0.4, the method supports revocation checking.
|
|
|
|
An authorized user can submit PEM-formatted CRLs identified by a given name;
|
|
these can be updated or deleted at will. They may also set the URL of a
|
|
trusted CRL distribution point, and have Vault fetch the CRL as needed.
|
|
|
|
When there are CRLs present, at the time of client authentication:
|
|
|
|
- If the client presents any chain where no certificate in the chain matches a
|
|
revoked serial number, authentication is allowed
|
|
|
|
- If there is no chain presented by the client without a revoked serial number,
|
|
authentication is denied
|
|
|
|
This method provides good security while also allowing for flexibility. For
|
|
instance, if an intermediate CA is going to be retired, a client can be
|
|
configured with two certificate chains: one that contains the initial
|
|
intermediate CA in the path, and the other that contains the replacement. When
|
|
the initial intermediate CA is revoked, the chain containing the replacement
|
|
will still allow the client to successfully authenticate.
|
|
|
|
**N.B.**: Matching is performed by _serial number only_. For most CAs,
|
|
including Vault's `pki` method, multiple CRLs can successfully be used as
|
|
serial numbers are globally unique. However, since RFCs only specify that
|
|
serial numbers must be unique per-CA, some CAs issue serial numbers in-order,
|
|
which may cause clashes if attempting to use CRLs from two such CAs in the same
|
|
mount of the method. The workaround here is to mount multiple copies of the
|
|
`cert` method, configure each with one CA/CRL, and have clients connect to the
|
|
appropriate mount.
|
|
|
|
In addition, if a CRL distribution point is not set the method will not
|
|
fetch the CRLs itself, the CRL's designated time to next update is not
|
|
considered. If a CRL is no longer in use, it is up to the administrator to
|
|
remove it from the method.
|
|
|
|
In addition to automatic or manual CRL management, OCSP may be enabled for
|
|
a configured certificate, in which case Vault will query the OCSP server either
|
|
specified in the presented certificate or configured in the auth method to
|
|
check revocation.
|
|
|
|
## Authentication
|
|
|
|
### Via the CLI
|
|
|
|
The below authenticates against the `web` cert role by presenting a certificate
|
|
(`cert.pem`) and key (`key.pem`) signed by the CA associated with the `web` cert
|
|
role. Note that the name `web` ties to the configuration example below writing
|
|
to a path of `auth/cert/certs/web`. If a certificate role name is not specified,
|
|
the auth method will try to authenticate against all trusted certificates.
|
|
|
|
~> **NOTE** The `-ca-cert` value used here is for the Vault TLS Listener CA
|
|
certificate, not the CA that issued the client authentication certificate. This
|
|
can be omitted if the CA used to issue the Vault server certificate is trusted
|
|
by the local system executing this command.
|
|
|
|
```shell-session
|
|
$ vault login \
|
|
-method=cert \
|
|
-ca-cert=vault-ca.pem \
|
|
-client-cert=cert.pem \
|
|
-client-key=key.pem \
|
|
name=web
|
|
```
|
|
|
|
### Via the API
|
|
|
|
The endpoint for the login is `/login`. The client simply connects with their
|
|
TLS certificate and when the login endpoint is hit, the auth method will
|
|
determine if there is a matching trusted certificate to authenticate the client.
|
|
Optionally, you may specify a single certificate role to authenticate against.
|
|
|
|
~> **NOTE** The `--cacert` value used here is for the Vault TLS Listener CA
|
|
certificate, not the CA that issued the client authentication certificate. This
|
|
can be omitted if the CA used to issue the Vault server certificate is trusted
|
|
by the local system executing this command.
|
|
|
|
```shell-session
|
|
$ curl \
|
|
--request POST \
|
|
--cacert vault-ca.pem \
|
|
--cert cert.pem \
|
|
--key key.pem \
|
|
--data '{"name": "web"}' \
|
|
https://127.0.0.1:8200/v1/auth/cert/login
|
|
```
|
|
|
|
## Configuration
|
|
|
|
Auth methods must be configured in advance before users or machines can
|
|
authenticate. These steps are usually completed by an operator or configuration
|
|
management tool.
|
|
|
|
1. Enable the certificate auth method:
|
|
|
|
```text
|
|
$ vault auth enable cert
|
|
```
|
|
|
|
1. Configure it with trusted certificates that are allowed to authenticate:
|
|
|
|
```text
|
|
$ vault write auth/cert/certs/web \
|
|
display_name=web \
|
|
policies=web,prod \
|
|
certificate=@web-cert.pem \
|
|
ttl=3600
|
|
```
|
|
|
|
This creates a new trusted certificate "web" with same display name and the
|
|
"web" and "prod" policies. The certificate (public key) used to verify
|
|
clients is given by the "web-cert.pem" file. Lastly, an optional `ttl` value
|
|
can be provided in seconds to limit the lease duration.
|
|
|
|
## API
|
|
|
|
The TLS Certificate auth method has a full HTTP API. Please see the
|
|
[TLS Certificate API](/vault/api-docs/auth/cert) for more details.
|