lsm_audit: avoid overloading the "key" audit field

The "key" field is used to associate records with the rule that
triggered them, os it's not a good idea to overload it with an
additional IPC key semantic. Moreover, as the classic "key" field is a
text field, while the IPC key is numeric, AVC records containing the IPC
key info actually confuse audit userspace, which tries to interpret the
number as a hex-encoded string, thus showing garbage for example in the
ausearch "interpret" output mode.

Hence, change it to "ipc_key" to fix both issues and also make the
meaning of this field more clear.
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/lsm_audit.c

@@ -224,7 +224,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 	case LSM_AUDIT_DATA_NONE:
 		return;
 	case LSM_AUDIT_DATA_IPC:
-		audit_log_format(ab, " key=%d ", a->u.ipc_id);
+		audit_log_format(ab, " ipc_key=%d ", a->u.ipc_id);
 		break;
 	case LSM_AUDIT_DATA_CAP:
 		audit_log_format(ab, " capability=%d ", a->u.cap);