KDC Audit infrastructure and plugin implementation

Per project http://k5wiki.kerberos.org/wiki/Projects/Audit

The purpose of this project is to create an Audit infrastructure to monitor
security related events on the KDC.

The following events are targeted in the initial version:
- startup and shutdown of the KDC;
- AS_REQ and TGS_REQ exchanges.  This includes client address and port, KDC
  request and request ID, KDC reply, primary and derived ticket and their
  ticket IDs, second ticket ID, cross-realm referral, was ticket renewed and
  validated, local policy violation and protocol constraints, and KDC status
  message.

Ticket ID is introduced to allow to link tickets to their initial TGT at any
stage of the Kerberos exchange. For the purpose of this project it is a private
to KDC ticket ID: each successfully created ticket is hashed and recorded
into audit log. The administrators can correlate the primary and derived
ticket IDs after the fact.

Request ID is a randomly generated alpha-numeric string. Using this ID an
administrator can easily correlate multiple audit events related to a single
request. It should be informative both in cases when the request is sent to
multiple KDCs, or to the same KDC multiple times.

For the purpose of testing and demo of the Audit, the JSON based modules are
implemented: "test" and "simple" audit modules respectively.
The file plugins/audit/j_dict.h is a dictionary used in this implememtations.

The new Audit system is build-time enabled and run-time pluggable.

[kaduk@mit.edu: remove potential KDC crashes, minor reordering]

ticket: 7712
target_version: 1.12

1 files changed, 26 insertions, 0 deletions

diff --git a/src/configure.in b/src/configure.in
index 81c684d16d..a4bf31aa8b 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -135,6 +135,30 @@ if test "$withval" = yes; then
 	AC_DEFINE(KRBCONF_VAGUE_ERRORS,1,[Define if the KDC should return only vague error codes to clients])
 fi
 
+# Check which (if any) audit plugin to build
+audit_plugin=""
+AC_ARG_ENABLE([audit-plugin],
+AC_HELP_STRING([--enable-audit-plugin=IMPL],
+               [use audit plugin @<:@ do not use audit @:>@]), , enableval=no)
+if test "$enableval" != no; then
+    case "$enableval" in
+    simple)
+        # if audit_log_user_message is found, we assume
+        # that audit_open and audit_close are also defined.
+        AC_CHECK_LIB(audit, audit_log_user_message,
+                     [AUDIT_IMPL_LIBS=-laudit
+                     K5_GEN_MAKEFILE(plugins/audit/simple)
+                     audit_plugin=plugins/audit/simple ],
+                     AC_MSG_ERROR([libaudit not found or undefined symbol audit_log_user_message]))
+        ;;
+    *)
+        AC_MSG_ERROR([Unknown audit plugin implementation $enableval.])
+        ;;
+    esac
+fi
+AC_SUBST(AUDIT_IMPL_LIBS)
+AC_SUBST(audit_plugin)
+
 # WITH_CRYPTO_IMPL
 
 CRYPTO_IMPL="builtin"
@@ -1362,6 +1386,8 @@ dnl	ccapi ccapi/lib ccapi/lib/unix ccapi/server ccapi/server/unix ccapi/test
 	plugins/localauth/test
 	plugins/kadm5_hook/test
 	plugins/pwqual/test
+	plugins/audit
+	plugins/audit/test
 	plugins/kdb/db2
 	plugins/kdb/db2/libdb2
 	plugins/kdb/db2/libdb2/hash