SSSD-SECRETS(5)

NAME
sssd-secrets - SSSD Secrets responder

DESCRIPTION

This manual page describes the configuration of the Secrets responder for sssd(8). For a detailed syntax reference, refer to the “FILE FORMAT” section of the sssd.conf(5) manual page.

Many system and user applications need to store private information such as passwords or service keys and have no good way to properly deal with them. The simple approach is to embed these “secrets” into configuration files potentially ending up exposing sensitive key material to backups, config management system and in general making it harder to secure data.

The custodia[1] project was born to deal with this problem in cloud like environments, but we found the idea compelling even at a single system level. As a security service, SSSD is ideal to host this capability while offering the same API via a Unix Socket. This will make it possible to use local calls and have them transparently routed to a local or a remote key management store like IPA Vault for storage, escrow and recovery.

The secrets are simple key-value pairs. Each user's secrets are namespaced using their user ID, which means the secrets will never collide between users. Secrets can be stored inside “containers” which can be nested.

USING THE SECRETS RESPONDER

The UNIX socket the SSSD responder listens on is located at /var/run/secrets.socket.

The secrets responder is socket-activated by systemd(1). Unlike other SSSD responders, it cannot be started by adding the “secrets” string to the “service” directive. The systemd socket unit is called “sssd-secrets.socket” and the corresponding service file is called “sssd-secrets.service”. In order for the service to be socket-activated, make sure the socket is enabled and active and the service is enabled:

    systemctl start sssd-secrets.socket
    systemctl enable sssd-secrets.socket
    systemctl enable sssd-secrets.service

Please note your distribution may already configure the units for you.

CONFIGURATION OPTIONS

The generic SSSD responder options such as “debug_level” or “fd_limit” are accepted by the secrets responder. Please refer to the sssd.conf(5) manual page for a complete list. In addition, there are some secrets-specific options as well.

provider (string)
    This option specifies where should the secrets be stored. The secrets responder can configure a per-user subsections that define which provider store the secrets for this particular user. The per-user subsections should contain all options for that user's provider. If a per-user section does not exist, the global settings from the secret responder's section are used. The following providers are supported:

    local
        The secrets are stored in a local database, encrypted at rest with a master key. The local provider does not have any additional config options at the moment.

    proxy
        The secrets responder forwards the requests to a Custodia server. The proxy provider supports several additional options (see below).

    Default: local

containers_nest_level (integer)
    This option specifies the maximum allowed number of nested containers.

    Default: 4

max_secrets (integer)
    This option specifies the maximum number of secrets that can be stored.

    Default: 1024

max_payload_size (integer)
    This option specifies the maximum payload size allowed for a secret payload in kilobytes.

    Default: 16

The following options are only applicable for configurations that use the “proxy” provider.

proxy_url (string)
    The URL the Custodia server is listening on. At the moment, http and https protocols are supported.

    The format of the URI must match the format defined in RFC 2732:

    http[s]://<host>[:port]

    Example: http://localhost:8080

auth_type (string)
    The method to use when authenticating to a Custodia server. The following authentication methods are supported:

    basic_auth
        Authenticate with a username and a password as set in the “username” and “password” options.

    header
        Authenticate with HTTP header value as defined in the “auth_header_name” and “auth_header_value” configuration options.

auth_header_name (string)
    If set, the secrets responder would put a header with this name into the HTTP request with the value defined in the “auth_header_value” configuration option.

    Example: MYSECRETNAME

auth_header_value (string)
    The value sssd-secrets would use for the “auth_header_name”.

    Example: mysecret

forward_headers (list of strings)
    The list of HTTP headers to forward to the Custodia server together with the request.

    Default: not set

USING THE REST API

This section lists the available commands and includes examples using the curl(1) utility. All requests towards the proxy provider must set the Content Type header to “application/json”. In addition, the local provider also supports Content Type set to “application/octet-stream”. Secrets stored with requests that set the Content Type header to “application/octet-stream” are base64-encoded when stored and decoded when retrieved, so it's not possible to store a secret with one Content Type and retrieve with another. The secret URI must begin with /secrets/.

Listing secrets
    To list the available secrets, send a HTTP GET request with a trailing slash appended to the container path.

    Example:

        curl -H "Content-Type: application/json" \
             --unix-socket /var/run/secrets.socket \
             -XGET http://localhost/secrets/

Retrieving a secret
    To read a value of a single secret, send a HTTP GET request without a trailing slash. The last portion of the URI is the name of the secret.

    Examples:

        curl -H "Content-Type: application/json" \
             --unix-socket /var/run/secrets.socket \
             -XGET http://localhost/secrets/foo

        curl -H "Content-Type: application/octet-stream" \
             --unix-socket /var/run/secrets.socket \
             -XGET http://localhost/secrets/bar

Setting a secret
    To set a secret using the “application/json” type, send a HTTP PUT request with a JSON payload that includes type and value. The type should be set to "simple" and the value should be set to the secret value. If a secret with that name already exists, the response is a 409 HTTP error.

    The “application/json” type just sends the secret as the message payload.

    The following example sets a secret named 'foo' to a value of 'foosecret' and a secret named 'bar' to a value of 'barsecret' using a different Content Type.

        curl -H "Content-Type: application/json" \
             --unix-socket /var/run/secrets.socket \
             -XPUT http://localhost/secrets/foo \
             -d'{"type":"simple","value":"foosecret"}'

        curl -H "Content-Type: application/octet-stream" \
             --unix-socket /var/run/secrets.socket \
             -XPUT http://localhost/secrets/bar \
             -d'barsecret'

Creating a container
    Containers provide an additional namespace for this user's secrets. To create a container, send a HTTP POST request, whose URI ends with the container name. Please note the URI must end with a trailing slash.

    The following example creates a container named 'mycontainer':

        curl -H "Content-Type: application/json" \
             --unix-socket /var/run/secrets.socket \
             -XPOST http://localhost/secrets/mycontainer/

    To manipulate secrets under this container, just nest the secrets underneath the container path:

        http://localhost/secrets/mycontainer/mysecret

Deleting a secret or a container
    To delete a secret or a container, send a HTTP DELETE request with a path to the secret or the container.

    The following example deletes a secret named 'foo'.

        curl -H "Content-Type: application/json" \
             --unix-socket /var/run/secrets.socket \
             -XDELETE http://localhost/secrets/foo

EXAMPLE CUSTODIA AND PROXY PROVIDER CONFIGURATION

For testing the proxy provider, you need to set up a Custodia server to proxy requests to. Please always consult the Custodia documentation, the configuration directives might change with different Custodia versions.

This configuration will set up a Custodia server listening on http://localhost:8080, allowing anyone with header named MYSECRETNAME set to mysecretkey to communicate with the Custodia server. Place the contents into a file (for example, custodia.conf):

    [global]
    server_version = "Secret/0.0.7"
    server_url = http://localhost:8080/
    auditlog = /var/log/custodia.log
    debug = True
    [store:simple]
    handler = custodia.store.sqlite.SqliteStore
    dburi = /var/lib/custodia.db
    table = secrets
    [auth:header]
    handler = custodia.httpd.authenticators.SimpleHeaderAuth
    header = MYSECRETNAME
    value = mysecretkey
    [authz:paths]
    handler = custodia.httpd.authorizers.SimplePathAuthz
    paths = /secrets
    [/]
    handler = custodia.root.Root
    store = simple

Then run the custodia command, pointing it at the config file as a command line argument.

Please note that currently it's not possible to proxy all requests globally to a Custodia instance. Instead, per-user subsections for user IDs that should proxy requests to Custodia must be defined. The following example illustrates a configuration, where the user with UID 123 would proxy their requests to Custodia, but all other user's requests would be handled by a local provider.

    [secrets]
    [secrets/users/123]
    provider = proxy
    proxy_url = http://localhost:8080/secrets/
    auth_type = header
    auth_header_name = MYSECRETNAME
    auth_header_value = mysecretkey

AUTHORS

The SSSD upstream - https://pagure.io/SSSD/sssd/

NOTES

1.  custodia
    https://github.com/latchset/custodia