fabric: Add support for job keys

Allow endpoints to be associated with an authorization key, commonly
referred to as a job key.  The auth_key optionally allows an endpoint
to restrict what traffic it accepts.  Only peers with a valid auth_key
can target a restricted endpoint.

Fixes ofiwg#2529

Architecturally, each endpoint can be associated with a single auth_key.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>

include/rdma/fabric.h

@@ -309,6 +309,8 @@ struct fi_ep_attr {
 	uint64_t		mem_tag_format;
 	size_t			tx_ctx_cnt;
 	size_t			rx_ctx_cnt;
+	size_t			auth_keylen;
+	uint8_t			*auth_key;
 };
 
 struct fi_domain_attr {

man/fi_endpoint.3.md

@@ -544,6 +544,8 @@ struct fi_ep_attr {
 	uint64_t        mem_tag_format;
 	size_t          tx_ctx_cnt;
 	size_t          rx_ctx_cnt;
+	size_t          auth_keylen;
+	uint8_t         *auth_key;
 };
 {% endhighlight %}
 
@@ -761,6 +763,21 @@ fail the request.
 See the scalable endpoint and shared contexts sections for additional
 details.
 
+## auth_keylen - Authorization Key Length
+
+The length of the authorization key.  This field will be 0 if
+authorization keys are not available or used.
+
+## auth_key - Authorization Key
+
+If supported by the fabric, an authorization key (a.k.a. job
+key) to associate with the endpoint.  An authorization key is used
+to limit communication between endpoints.  Only peer endpoints that are
+programmed to use the same authorization key may communicate.
+Authorization keys are often used to implement job keys, to ensure
+that processes running in different jobs do not accidentally
+cross traffic.
+
 # TRANSMIT CONTEXT ATTRIBUTES
 
 Attributes specific to the transmit capabilities of an endpoint are