detect: add ldap.responses.attribute_type

ldap.responses.attribute_type matches on LDAP attribute type/description
This keyword maps the eve field ldap.responses[].search_result_entry.attributes[].type
It is a sticky buffer
Supports multiple buffer matching
Supports prefiltering

Ticket: #7533

doc/userguide/rules/ldap-keywords.rst

@@ -498,3 +498,40 @@ add request operation and contains the LDAP attribute type
 .. container:: example-rule
 
   alert ldap any any -> any any (msg:"Test attribute type and operation"; :example-rule-emphasis:`ldap.request.operation:add_request; ldap.request.attribute_type; content:"objectClass";` sid:1;)
+
+ldap.responses.attribute_type
+-----------------------------
+
+Matches on LDAP attribute type from response operations.
+
+Comparison is case-sensitive.
+
+Syntax::
+
+ ldap.responses.attribute_type; content:"<content to match against>";
+
+``ldap.responses.attribute_type`` is a 'sticky buffer' and can be used as a ``fast_pattern``.
+
+``ldap.responses.attribute_type`` supports multiple buffer matching, see :doc:`multi-buffer-matching`.
+
+This keyword maps to the EVE field ``ldap.responses[].search_result_entry.attributes[].type``
+
+Example
+^^^^^^^
+
+Example of a signature that would alert if a packet has the LDAP attribute type ``dc``:
+
+.. container:: example-rule
+
+  alert ldap any any -> any any (msg:"Test responses attribute type"; :example-rule-emphasis:`ldap.responses.attribute_type; content:"dc";` sid:1;)
+
+It is possible to use the keyword ``ldap.responses.operation`` in the same rule to
+specify the operation to match.
+
+Here is an example of a signature that would alert if a packet has an LDAP
+search result entry operation at index 1 on the responses array,
+and contains the LDAP attribute type ``dc``.
+
+.. container:: example-rule
+
+  alert ldap any any -> any any (msg:"Test attribute type and operation"; :example-rule-emphasis:`ldap.responses.operation:search_result_entry,1; ldap.responses.attribute_type; content:"dc";` sid:1;)

doc/userguide/rules/multi-buffer-matching.rst

@@ -87,6 +87,7 @@ following keywords:
 * ``krb5_cname``
 * ``krb5_sname``
 * ``ldap.request.attribute_type``
+* ``ldap.responses.attribute_type``
 * ``ldap.responses.dn``
 * ``ldap.responses.message``
 * ``mqtt.subscribe.topic``

rust/src/ldap/detect.rs

@@ -71,6 +71,7 @@ static mut G_LDAP_RESPONSES_RESULT_CODE_KW_ID: c_int = 0;
 static mut G_LDAP_RESPONSES_RESULT_CODE_BUFFER_ID: c_int = 0;
 static mut G_LDAP_RESPONSES_MSG_BUFFER_ID: c_int = 0;
 static mut G_LDAP_REQUEST_ATTRIBUTE_TYPE_BUFFER_ID: c_int = 0;
+static mut G_LDAP_RESPONSES_ATTRIBUTE_TYPE_BUFFER_ID: c_int = 0;
 
 unsafe extern "C" fn ldap_parse_protocol_req_op(
     ustr: *const std::os::raw::c_char,
@@ -635,6 +636,59 @@ unsafe extern "C" fn ldap_tx_get_req_attribute_type(
     return false;
 }
 
+unsafe extern "C" fn ldap_detect_responses_attibute_type_setup(
+    de: *mut c_void, s: *mut c_void, _raw: *const std::os::raw::c_char,
+) -> c_int {
+    if DetectSignatureSetAppProto(s, ALPROTO_LDAP) != 0 {
+        return -1;
+    }
+    if DetectBufferSetActiveList(de, s, G_LDAP_RESPONSES_ATTRIBUTE_TYPE_BUFFER_ID) < 0 {
+        return -1;
+    }
+    return 0;
+}
+
+unsafe extern "C" fn ldap_detect_responses_attribute_type_get_data(
+    de: *mut c_void, transforms: *const c_void, flow: *const c_void, flow_flags: u8,
+    tx: *const c_void, list_id: c_int, local_id: u32,
+) -> *mut c_void {
+    return DetectHelperGetMultiData(
+        de,
+        transforms,
+        flow,
+        flow_flags,
+        tx,
+        list_id,
+        local_id,
+        ldap_tx_get_resp_attribute_type,
+    );
+}
+
+unsafe extern "C" fn ldap_tx_get_resp_attribute_type(
+    tx: *const c_void, _flags: u8, local_id: u32, buffer: *mut *const u8, buffer_len: *mut u32,
+) -> bool {
+    let tx = cast_pointer!(tx, LdapTransaction);
+
+    let mut pos = 0_u32;
+    for i in 0..tx.responses.len() {
+        let response = &tx.responses[i];
+        match &response.protocol_op {
+            ProtocolOp::SearchResultEntry(resp) => {
+                if local_id < pos + resp.attributes.len() as u32 {
+                    let value = &resp.attributes[(local_id - pos) as usize].attr_type.0;
+                    *buffer = value.as_ptr(); //unsafe
+                    *buffer_len = value.len() as u32;
+                    return true;
+                } else {
+                    pos += resp.attributes.len() as u32;
+                }
+            }
+            _ => continue,
+        }
+    }
+    return false;
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn SCDetectLdapRegister() {
     let kw = SCSigTableElmt {
@@ -776,4 +830,23 @@ pub unsafe extern "C" fn SCDetectLdapRegister() {
         true,  //to server
         ldap_detect_request_attribute_type_get_data,
     );
+    let kw = SCSigTableElmt {
+        name: b"ldap.responses.attribute_type\0".as_ptr() as *const libc::c_char,
+        desc: b"match LDAP responses attribute type\0".as_ptr() as *const libc::c_char,
+        url: b"/rules/ldap-keywords.html#ldap.responses.attribute_type\0".as_ptr()
+            as *const libc::c_char,
+        Setup: ldap_detect_responses_attibute_type_setup,
+        flags: SIGMATCH_NOOPT | SIGMATCH_INFO_STICKY_BUFFER,
+        AppLayerTxMatch: None,
+        Free: None,
+    };
+    let _g_ldap_responses_attribute_type_kw_id = DetectHelperKeywordRegister(&kw);
+    G_LDAP_RESPONSES_ATTRIBUTE_TYPE_BUFFER_ID = DetectHelperMultiBufferMpmRegister(
+        b"ldap.responses.attribute_type\0".as_ptr() as *const libc::c_char,
+        b"LDAP RESPONSES ATTRIBUTE TYPE\0".as_ptr() as *const libc::c_char,
+        ALPROTO_LDAP,
+        true,  //to client
+        false, //to server
+        ldap_detect_responses_attribute_type_get_data,
+    );
 }