sssd-secrets 5 File Formats and Conventions sssd-secrets SSSD Secrets responder 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 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. Since the secrets responder can be used both externally to store general secrets, as described in the rest of this man page, but also internally by other SSSD components to store their secret material, some configuration options, like quotas can be configured per hive in a configuration subsection named after the hive. The currently supported hives are: secrets secrets for general usage kcm used by the sssd-kcm 8 service. 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. 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. The secrets responder is configured with a global [secrets] section and an optional per-user [secrets/users/$uid] section in sssd.conf. Please note that some options, notably as the provider type, can only be specified in the per-user subsections. provider (string) This option specifies where should the secrets be stored. The secrets responder can configure a per-user subsections (e.g. [secrets/users/123] - see bottom of this manual page for a full example using Custodia for a particular user) that define which provider store the secrets for this particular user. The per-user subsections should contain all options for that user's provider. Please note that currently the global provider is always local, the proxy provider can only be specified in a per-user section. 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 The following options affect only the secrets hive and therefore should be set in a per-hive subsection. Setting the option to 0 means "unlimited". 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 in the hive. Default: 1024 (secrets hive), 256 (kcm hive) max_uid_secrets (integer) This option specifies the maximum number of secrets that can be stored per-UID in the hive. Default: 256 (secrets hive), 64 (kcm hive) max_payload_size (integer) This option specifies the maximum payload size allowed for a secret payload in kilobytes. Default: 16 (secrets hive), 65536 (64 MiB) (kcm hive) For example, to adjust quotas differently for both the secrets and the kcm hives, configure the following: [secrets/secrets] max_payload_size = 128 [secrets/kcm] max_payload_size = 256 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 verify_peer (boolean) Whether peer's certificate should be verified and valid if HTTPS protocol is used with the proxy provider. Default: true verify_host (boolean) Whether peer's hostname must match with hostname in its certificate if HTTPS protocol is used with the proxy provider. Default: true capath (string) Path to directory containing stored certificate authority certificates. System default path is used if this option is not set. Default: not set cacert (string) Path to file containing server's certificate authority certificate. If this option is not set then the CA's certificate is looked up in capath. Default: not set cert (string) Path to file containing client's certificate if required by the server. This file may also contain private key or the private key may be in separate file set with key. Default: not set key (string) Path to file containing client's private key. Default: not set 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 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