Extend documentation in default.properties and LdapKeyManager.java.

Author: fzs

src/main/distrib/data/defaults.properties

@@ -1938,7 +1938,11 @@ realm.ldap.uid = uid
 # Attribute on the USER record that indicates their public SSH key.
 # Leave blank when public SSH keys shall not be retrieved from LDAP.
 #
-# This may be a simple attribute or an attribute and a value prefix. Examples:
+# This setting is only relevant when a public key manager is used that
+# retrieves SSH keys from LDAP (e.g. com.gitblit.transport.ssh.LdapKeyManager).
+#
+# The accepted format of the value is dependent on the public key manager used.
+# Examples:
 #  sshPublicKey - Use the attribute 'sshPublicKey' on the user record.
 #  altSecurityIdentities:SshKey - Use the attribute 'altSecurityIdentities'
 #                                 on the user record, for which the record value

src/main/java/com/gitblit/transport/ssh/LdapKeyManager.java

@@ -44,11 +44,36 @@
 import com.unboundid.ldap.sdk.SearchResultEntry;
 
 /**
- * LDAP public key manager
+ * LDAP-only public key manager
  *
  * Retrieves public keys from user's LDAP entries. Using this key manager,
  * no SSH keys can be edited, i.e. added, removed, permissions changed, etc.
  *
+ * This key manager supports SSH key entries in LDAP of the following form:
+ * [<prefix>:] [<options>] <type> <key> [<comment>]
+ * This follows the required form of entries in the authenticated_keys file,
+ * with an additional optional prefix. Key entries must have a key type
+ * (like "ssh-rsa") and a key, and may have a comment at the end.
+ *
+ * An entry may specify login options as specified for the authorized_keys file.
+ * The 'environment' option may be used to set the permissions for the key
+ * by setting a 'gbPerm' environment variable. The key manager will interpret
+ * such a environment variable option and use the set permission string to set
+ * the permission on the key in Gitblit. Example:
+ *   environment="gbPerm=V",pty ssh-rsa AAAxjka.....dv= Clone only key
+ * Above entry would create a RSA key with the comment "Clone only key" and
+ * set the key permission to CLONE. All other options are ignored.
+ *
+ * In Active Directory SSH public keys are sometimes stored in the attribute
+ * 'altSecurityIdentity'. The attribute value is usually prefixed by a type
+ * identifier. LDAP entries could have the following attribute values:
+ *   altSecurityIdentity: X.509: ADKEJBAKDBZUPABBD...
+ *   altSecurityIdentity: SshKey: ssh-dsa AAAAknenazuzucbhda...
+ * This key manager supports this by allowing an optional prefix to identify
+ * SSH keys. The prefix to be used should be set in the 'realm.ldap.sshPublicKey'
+ * setting by separating it from the attribute name with a colon, e.g.:
+ *    realm.ldap.sshPublicKey = altSecurityIdentity:SshKey
+ *
  * @author Florian Zschocke
  *
  */