stream/reassemble: add exception policy counters

Add stats counters for exception policies applied in case of memcap hit
during stream reassembly.

Task #5816

etc/schema.json

@@ -5367,6 +5367,11 @@
                         "pseudo_failed": {
                             "type": "integer"
                         },
+                        "reassembly_exception_policy": {
+                            "description":
+                                    "How many times reassembly memcap exception policy was applied, and which one",
+                            "$ref": "#/$defs/exceptionPolicy"
+                        },
                         "reassembly_gap": {
                             "type": "integer"
                         },

src/stream-tcp-reassemble.c

@@ -1,4 +1,4 @@
-/* Copyright (C) 2007-2022 Open Information Security Foundation
+/* Copyright (C) 2007-2024 Open Information Security Foundation
  *
  * You can copy, redistribute or modify this Program under the terms of
  * the GNU General Public License version 2 as published by the Free
@@ -1949,6 +1949,15 @@ static int StreamTcpReassembleHandleSegmentUpdateACK (ThreadVars *tv,
     SCReturnInt(0);
 }
 
+static void StreamTcpReassembleExceptionPolicyStatsIncr(
+        ThreadVars *tv, TcpReassemblyThreadCtx *ra_ctx, enum ExceptionPolicy policy)
+{
+    uint16_t id = ra_ctx->counter_tcp_reas_eps.eps_id[policy];
+    if (likely(tv && id > 0)) {
+        StatsIncr(tv, id);
+    }
+}
+
 int StreamTcpReassembleHandleSegment(ThreadVars *tv, TcpReassemblyThreadCtx *ra_ctx,
         TcpSession *ssn, TcpStream *stream, Packet *p)
 {
@@ -2015,6 +2024,8 @@ int StreamTcpReassembleHandleSegment(ThreadVars *tv, TcpReassemblyThreadCtx *ra_
             /* failure can only be because of memcap hit, so see if this should lead to a drop */
             ExceptionPolicyApply(
                     p, stream_config.reassembly_memcap_policy, PKT_DROP_REASON_STREAM_REASSEMBLY);
+            StreamTcpReassembleExceptionPolicyStatsIncr(
+                    tv, ra_ctx, stream_config.reassembly_memcap_policy);
             SCReturnInt(-1);
         }
 

src/stream-tcp-reassemble.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2007-2010 Open Information Security Foundation
+/* Copyright (C) 2007-2024 Open Information Security Foundation
  *
  * You can copy, redistribute or modify this Program under the terms of
  * the GNU General Public License version 2 as published by the Free
@@ -28,6 +28,7 @@
 #include "suricata.h"
 #include "flow.h"
 #include "stream-tcp-private.h"
+#include "util-exception-policy.h"
 
 /** Supported OS list and default OS policy is BSD */
 enum
@@ -64,6 +65,8 @@ typedef struct TcpReassemblyThreadCtx_ {
 
     /** TCP segments which are not being reassembled due to memcap was reached */
     uint16_t counter_tcp_segment_memcap;
+    /** times exception policy for stream reassembly memcap was applied **/
+    ExceptionPolicyCounters counter_tcp_reas_eps;
 
     uint16_t counter_tcp_segment_from_cache;
     uint16_t counter_tcp_segment_from_pool;

src/stream-tcp.c

@@ -1,4 +1,4 @@
-/* Copyright (C) 2007-2023 Open Information Security Foundation
+/* Copyright (C) 2007-2024 Open Information Security Foundation
  *
  * You can copy, redistribute or modify this Program under the terms of
  * the GNU General Public License version 2 as published by the Free
@@ -116,6 +116,32 @@ ExceptionPolicyStatsSetts stream_memcap_eps_stats = {
 };
 // clang-format on
 
+/* Settings order as in the enum */
+// clang-format off
+ExceptionPolicyStatsSetts stream_reassembly_memcap_eps_stats = {
+    .valid_settings_ids = {
+    /* EXCEPTION_POLICY_NOT_SET */      false,
+    /* EXCEPTION_POLICY_AUTO */         false,
+    /* EXCEPTION_POLICY_PASS_PACKET */  true,
+    /* EXCEPTION_POLICY_PASS_FLOW */    true,
+    /* EXCEPTION_POLICY_BYPASS_FLOW */  true,
+    /* EXCEPTION_POLICY_DROP_PACKET */  false,
+    /* EXCEPTION_POLICY_DROP_FLOW */    false,
+    /* EXCEPTION_POLICY_REJECT */       true,
+    },
+    .valid_settings_ips = {
+    /* EXCEPTION_POLICY_NOT_SET */      false,
+    /* EXCEPTION_POLICY_AUTO */         false,
+    /* EXCEPTION_POLICY_PASS_PACKET */  true,
+    /* EXCEPTION_POLICY_PASS_FLOW */    true,
+    /* EXCEPTION_POLICY_BYPASS_FLOW */  true,
+    /* EXCEPTION_POLICY_DROP_PACKET */  true,
+    /* EXCEPTION_POLICY_DROP_FLOW */    true,
+    /* EXCEPTION_POLICY_REJECT */       true,
+    },
+};
+// clang-format on
+
 static int StreamTcpHandleFin(ThreadVars *tv, StreamTcpThread *, TcpSession *, Packet *);
 void StreamTcpReturnStreamSegments (TcpStream *);
 void StreamTcpInitConfig(bool);
@@ -728,6 +754,14 @@ void StreamTcpFreeConfig(bool quiet)
     SCLogDebug("ssn_pool_cnt %"PRIu64"", ssn_pool_cnt);
 }
 
+static bool IsReassemblyMemcapExceptionPolicyStatsValid(enum ExceptionPolicy exception_policy)
+{
+    if (EngineModeIsIPS()) {
+        return stream_reassembly_memcap_eps_stats.valid_settings_ips[exception_policy];
+    }
+    return stream_reassembly_memcap_eps_stats.valid_settings_ids[exception_policy];
+}
+
 static bool IsStreamTcpSessionMemcapExceptionPolicyStatsValid(enum ExceptionPolicy policy)
 {
     if (EngineModeIsIPS()) {
@@ -5825,6 +5859,11 @@ TmEcode StreamTcpThreadInit(ThreadVars *tv, void *initdata, void **data)
         SCReturnInt(TM_ECODE_FAILED);
 
     stt->ra_ctx->counter_tcp_segment_memcap = StatsRegisterCounter("tcp.segment_memcap_drop", tv);
+
+    ExceptionPolicySetStatsCounters(tv, &stt->ra_ctx->counter_tcp_reas_eps,
+            &stream_reassembly_memcap_eps_stats, stream_config.reassembly_memcap_policy,
+            "tcp.reassembly_exception_policy.", IsReassemblyMemcapExceptionPolicyStatsValid);
+
     stt->ra_ctx->counter_tcp_segment_from_cache =
             StatsRegisterCounter("tcp.segment_from_cache", tv);
     stt->ra_ctx->counter_tcp_segment_from_pool = StatsRegisterCounter("tcp.segment_from_pool", tv);