snmp/detect: add snmp.trap_address keyword

Ticket: 8486

doc/userguide/rules/snmp-keywords.rst

@@ -137,4 +137,21 @@ Syntax::
 
 ``snmp.trap_oid`` is a 'sticky buffer'.
 
-``snmp.trap_oid`` can be used as ``fast_pattern``.
+``snmp.trap_oid`` can be used as ``fast_pattern``.
+
+snmp.trap_address
+-----------------
+
+SNMP Trap Address is the IP address of the agent.
+
+Syntax::
+
+ snmp.trap_address; content:"192.168.1.2";
+
+.. container:: example-rule
+
+ alert snmp any any -> any any (msg:"SNMP trap address example"; snmp.trap_address; content:"192.168.1.2"; sid:4; rev:1;)
+
+``snmp.trap_address`` is a 'sticky buffer'.
+
+``snmp.trap_address`` can be used as ``fast_pattern``.

etc/schema.json

@@ -6156,7 +6156,12 @@
                     }
                 },
                 "trap_address": {
-                    "type": "string"
+                    "type": "string",
+                    "suricata": {
+                        "keywords": [
+                            "snmp.trap_address"
+                        ]
+                    }
                 },
                 "trap_oid": {
                     "type": "string",

rust/src/snmp/detect.rs

@@ -28,6 +28,7 @@ use crate::detect::{
     SCDetectThreadBufDataInit, SigTableElmtStickyBuffer, SIGMATCH_INFO_ENUM_UINT,
     SIGMATCH_INFO_UINT32, SIGMATCH_INFO_UINT8, SIGMATCH_SUPPORT_FIREWALL,
 };
+use snmp_parser::NetworkAddress;
 use std::ffi::CStr;
 use std::os::raw::{c_int, c_void};
 use suricata_sys::sys::{
@@ -46,6 +47,8 @@ static mut G_SNMP_USM_BUFFER_ID: c_int = 0;
 static mut G_SNMP_COMMUNITY_BUFFER_ID: c_int = 0;
 static mut G_SNMP_TRAPOID_BUFFER_ID: c_int = 0;
 static mut G_SNMP_TRAPOID_THREAD_ID: c_int = 0;
+static mut G_SNMP_TRAPADDRESS_BUFFER_ID: c_int = 0;
+static mut G_SNMP_TRAPADDRESS_THREAD_ID: c_int = 0;
 static mut G_SNMP_TRAPTYPE_KW_ID: u16 = 0;
 static mut G_SNMP_GENERIC_BUFFER_ID: c_int = 0;
 
@@ -304,6 +307,48 @@ unsafe extern "C" fn snmp_detect_trapoid_get_data(
     return buffer;
 }
 
+unsafe extern "C" fn snmp_detect_trapaddress_setup(
+    de: *mut DetectEngineCtx, s: *mut Signature, _raw: *const std::os::raw::c_char,
+) -> c_int {
+    if SCDetectSignatureSetAppProto(s, ALPROTO_SNMP) != 0 {
+        return -1;
+    }
+    if SCDetectBufferSetActiveList(de, s, G_SNMP_TRAPADDRESS_BUFFER_ID) < 0 {
+        return -1;
+    }
+    return 0;
+}
+
+unsafe extern "C" fn snmp_detect_trapaddress_get_data(
+    det_ctx: *mut DetectEngineThreadCtx, transforms: *const DetectEngineTransforms,
+    _flow: *mut Flow, _dir: u8, tx: *mut c_void, list_id: c_int,
+) -> *mut InspectionBuffer {
+    let tx = cast_pointer!(tx, SNMPTransaction);
+    let buffer = SCInspectionBufferGet(det_ctx, list_id);
+    if !(*buffer).initialized {
+        if let Some(info) = &tx.info {
+            if let Some((_trap_type, _oid, address)) = &info.trap_type {
+                let NetworkAddress::IPv4(ip) = &address;
+                let tbuf = SCDetectThreadCtxGetGlobalKeywordThreadCtx(
+                    det_ctx,
+                    G_SNMP_TRAPADDRESS_THREAD_ID,
+                );
+                let tbuf = cast_pointer!(tbuf, DetectThreadBuf);
+                tbuf.data.clear();
+                tbuf.data.extend_from_slice(ip.to_string().as_bytes());
+                let data = tbuf.data.as_ptr();
+                let data_len = tbuf.data.len() as u32;
+                SCInspectionBufferSetupAndApplyTransforms(
+                    det_ctx, list_id, buffer, data, data_len, transforms,
+                );
+                return buffer;
+            }
+        }
+        return std::ptr::null_mut();
+    }
+    return buffer;
+}
+
 pub(super) unsafe extern "C" fn detect_snmp_register() {
     G_SNMP_GENERIC_BUFFER_ID = SCDetectHelperBufferProgressRegister(
         b"snmp.generic\0".as_ptr() as *const libc::c_char,
@@ -397,4 +442,26 @@ pub(super) unsafe extern "C" fn detect_snmp_register() {
         std::ptr::null_mut(),
         Some(SCDetectThreadBufDataFree),
     );
+
+    let kw = SigTableElmtStickyBuffer {
+        name: String::from("snmp.trap_address"),
+        desc: String::from("SNMP trap address sticky buffer"),
+        url: String::from("/rules/snmp-keywords.html#snmp-trap-address"),
+        setup: snmp_detect_trapaddress_setup,
+    };
+    let _g_snmp_trapaddress_kw_id = helper_keyword_register_sticky_buffer(&kw);
+    G_SNMP_TRAPADDRESS_BUFFER_ID = SCDetectRegisterMpmGeneric(
+        b"snmp.trap_address\0".as_ptr() as *const libc::c_char,
+        b"SNMP Trap Address\0".as_ptr() as *const libc::c_char,
+        ALPROTO_SNMP,
+        STREAM_TOSERVER | STREAM_TOCLIENT,
+        Some(snmp_detect_trapaddress_get_data),
+        1,
+    );
+    G_SNMP_TRAPADDRESS_THREAD_ID = SCDetectRegisterThreadCtxGlobalFuncs(
+        b"snmp.trap_address\0".as_ptr() as *const libc::c_char,
+        Some(SCDetectThreadBufDataInit),
+        std::ptr::null_mut(),
+        Some(SCDetectThreadBufDataFree),
+    );
 }