feat: add a private enterprise SD-ELEMENT for the log pipeline

CMakeLists.txt

@@ -138,6 +138,7 @@ add_executable(baseline
     ${APP_DIR}/storage/SemihostingDisk.c
     ${APP_DIR}/syslog/Syslog.c
     ${APP_DIR}/syslog/SyslogFields.c
+    ${APP_DIR}/syslog/SyslogPipelineSd.c
     ${APP_DIR}/syslog/SyslogErrorHandler.c
     $<TARGET_OBJECTS:baseline_upstream>
 )

README.md

@@ -10,17 +10,21 @@ It builds on a baseline that simulates the sort of device you might be adding th
 measures itself: see [docs/baseline.md](docs/baseline.md) for what the baseline is, how the
 figures are made, and how to run it.
 
-## This stage — HMAC at rest
+## This stage — Private SD-ELEMENT
 
-Stored records are sealed with HMAC-SHA256 instead of a CRC-16. An edit made on the volume no
-longer verifies, so the spool becomes tamper-evident rather than merely checked for corruption.
+RFC 5424 records carry structured data: named groups of key/value pairs a collector parses rather
+than pattern-matches out of the message text. Everything used so far has been standard elements,
+which mean the same on any device. This stage defines one of our own — which is where a product
+says what only it knows, and `app/syslog/SyslogPipelineSd.c` is all it takes to write one.
 
-The key is the device's own, fetched from its provisioned key store for each seal and each verify
-rather than held by the logger.
+`logPipeline@32473` reports the protection the record's own path was under: `transport="tls"`,
+`atRest="hmac-sha256"`, under our IANA enterprise number so a private name cannot collide with
+anyone else's. A collector can confirm that rather than assume it, and alert on a device whose
+pipeline has weakened.
 
 <!-- STAGE-COST:START (generated by scripts/gen-cost-table.py — do not edit by hand) -->
 
-**Cost above baseline: Flash +13,424 B, RAM +35,684 B.**
+**Cost above baseline: Flash +13,548 B, RAM +35,688 B.**
 
 <!-- STAGE-COST:END -->
 
@@ -51,6 +55,7 @@ committed as [`run-report.md`](run-report.md), and rewritten by every stage.
 | Origin address | the device's own address in the record, which a relay or NAT between it and the collector cannot rewrite | +12,388 | +7,384 |
 | TLS | a collector the device authenticates, and records no longer readable on the wire | +13,076 | +35,664 |
 | HMAC at rest | stored records that cannot be edited undetected, not merely checked for corruption | +13,424 | +35,684 |
+| Private SD-ELEMENT | a record that states the protection its own log pipeline was under | +13,548 | +35,688 |
 
 *Deltas are bytes above the baseline, which is itself Flash 350,308 B, RAM 111,192 B.*
 

app/syslog/Syslog.c

@@ -35,6 +35,7 @@
 #include "SolidSyslogTimeQualitySd.h"
 #include "SyslogEnterprise.h"
 #include "SyslogFields.h"
+#include "SyslogPipelineSd.h"
 
 #include "lwip/ip4_addr.h"
 #include "lwip/tcpip.h"
@@ -69,7 +70,7 @@ static struct SolidSyslog* s_logger = NULL;
 static uint8_t s_ring[SOLIDSYSLOG_CIRCULAR_BUFFER_RING_BYTES(SYSLOG_BUFFER_RECORDS)];
 
 /* The logger reads these on every record, so they outlive Syslog_Start. */
-static struct SolidSyslogStructuredData* s_sd[3];
+static struct SolidSyslogStructuredData* s_sd[4];
 
 /* One reading at boot, then free-running on the tick — enough to stamp a record,
  * not synchronisation. */
@@ -182,6 +183,7 @@ void Syslog_Start(void)
         .GetIpAt = SyslogOriginIpAt,
     };
     s_sd[2] = SolidSyslogOriginSd_Create(&originConfig);
+    s_sd[3] = SyslogPipelineSd_Get();
 
     struct SolidSyslogMbedTlsHmacSha256PolicyConfig hmacConfig = {.GetKey = SyslogStoreKey};
 

app/syslog/SyslogEnterprise.h

@@ -1,12 +1,16 @@
-/* This product's IANA Private Enterprise Number. It identifies the vendor, not
- * the logger, so it lives on its own rather than beside any one element that
- * carries it.
+/* This product's IANA Private Enterprise Number, in the two forms RFC 5424 wants
+ * it: the number that makes a private SD-ID private, and the string origin's
+ * enterpriseId PARAM carries. Defined once and derived, so the two cannot drift.
  *
  * 32473 is reserved for documentation (RFC 5612). Register your own at
  * https://www.iana.org/assignments/enterprise-numbers/ */
 #ifndef APP_SYSLOG_ENTERPRISE_H
 #define APP_SYSLOG_ENTERPRISE_H
 
-#define SYSLOG_ENTERPRISE_ID "32473"
+#define SYSLOG_ENTERPRISE_NUMBER 32473
+
+#define SYSLOG_ENTERPRISE_STRINGIFY_(value) #value
+#define SYSLOG_ENTERPRISE_STRINGIFY(value) SYSLOG_ENTERPRISE_STRINGIFY_(value)
+#define SYSLOG_ENTERPRISE_ID SYSLOG_ENTERPRISE_STRINGIFY(SYSLOG_ENTERPRISE_NUMBER)
 
 #endif /* APP_SYSLOG_ENTERPRISE_H */

app/syslog/SyslogPipelineSd.c

@@ -0,0 +1,30 @@
+/* See SyslogPipelineSd.h. */
+
+#include "SyslogPipelineSd.h"
+
+#include "SyslogEnterprise.h"
+
+#include "SolidSyslogSdElement.h"
+#include "SolidSyslogSdValue.h"
+#include "SolidSyslogStructuredDataDefinition.h"
+
+/* A non-zero enterprise number is what makes the SD-ID private: _Begin emits
+ * "name@number" for one, a bare IANA "name" for 0. */
+static void SyslogPipelineSd_Format(struct SolidSyslogStructuredData* base, struct SolidSyslogSdElement* element)
+{
+    (void) base;
+
+    SolidSyslogSdElement_Begin(element, "logPipeline", SYSLOG_ENTERPRISE_NUMBER);
+    SolidSyslogSdValue_String(SolidSyslogSdElement_Param(element, "transport"), "tls");
+    SolidSyslogSdValue_String(SolidSyslogSdElement_Param(element, "atRest"), "hmac-sha256");
+    SolidSyslogSdElement_End(element);
+}
+
+/* No _Create and no pool slot: the library never allocates an SD source, so a
+ * stateless one is a vtable this application owns. */
+static struct SolidSyslogStructuredData s_pipelineSd = {SyslogPipelineSd_Format};
+
+struct SolidSyslogStructuredData* SyslogPipelineSd_Get(void)
+{
+    return &s_pipelineSd;
+}

app/syslog/SyslogPipelineSd.h

@@ -0,0 +1,13 @@
+/* A worked example of a private enterprise SD-ELEMENT — the part of RFC 5424
+ * structured data that is yours to define. The IANA elements say what any device
+ * can say; a private one says what only your product knows. This one reports the
+ * protection in force on the log pipeline itself. */
+#ifndef APP_SYSLOG_PIPELINE_SD_H
+#define APP_SYSLOG_PIPELINE_SD_H
+
+struct SolidSyslogStructuredData;
+
+/** The shared instance, for SolidSyslogConfig.Sd. Stateless, so never NULL. */
+struct SolidSyslogStructuredData* SyslogPipelineSd_Get(void);
+
+#endif /* APP_SYSLOG_PIPELINE_SD_H */

measurements/pipeline-sd.csv

@@ -0,0 +1,13 @@
+# pipeline-sd figures (bytes) — captured by scripts/run.sh (CAPTURE=1).
+# The device reads measurements/Baseline.csv as its frozen baseline and reports current-minus-Baseline.
+flash_text,363208
+flash_data,648
+static_bss,146232
+heap_used,4440
+mbedtls_peak,36096
+mbedtls_free,18176
+lwip_mem_free,7576
+lwip_pbufs_free,14
+stack_log,832
+stack_service,3852
+stack_harness,2848

measurements/stages.tsv

@@ -27,3 +27,4 @@ buffer-halve	Smaller ring	most of the cap rise given back, now the store rather
 origin-ip	Origin address	the device's own address in the record, which a relay or NAT between it and the collector cannot rewrite
 tls	TLS	a collector the device authenticates, and records no longer readable on the wire
 hmac	HMAC at rest	stored records that cannot be edited undetected, not merely checked for corruption
+pipeline-sd	Private SD-ELEMENT	a record that states the protection its own log pipeline was under

run-report.md

@@ -1,4 +1,4 @@
-# solid-syslog-example — run (hmac)
+# solid-syslog-example — run (pipeline-sd)
 
 ## Device (self-measured)
 
@@ -10,14 +10,14 @@
 [device]   first record logged: yes
 [report] --- SolidSyslog cost above baseline (simulated existing application) ---
 [report] key,current,baseline,used_above_baseline
-[report] flash_text,363088,349992,13096
-[report] flash_data,644,316,328
+[report] flash_text,363208,349992,13216
+[report] flash_data,648,316,332
 [report] static_bss,146232,110876,35356
 [report] heap_used,4440,4440,0
 [report] mbedtls_peak,36096,21332,14764
 [report] mbedtls_free,18176,11436,6740
 [report] lwip_mem_free,7576,7576,0
-[report] lwip_pbufs_free,13,14,-1
+[report] lwip_pbufs_free,14,14,0
 [report] stack_log,832,120,712
 [report] stack_service,3852,52,3800
 [report] stack_harness,2848,2840,8
@@ -29,7 +29,7 @@
 
 ```text
    text	   data	    bss	    dec	    hex	filename
- 363080	    652	 146232	 509964	  7c80c	/w/build/baseline-cross/baseline.elf
+ 363200	    656	 146232	 510088	  7c888	/w/build/baseline-cross/baseline.elf
 ```
 
 ## Listeners (proved before the device ran)
@@ -47,21 +47,21 @@
 ## Collector (syslog-ng) received
 
 ```text
-wire   <134>1 2026-07-29T10:49:57.430000Z 10.0.2.15 solid-syslog-example - BOOT [meta sequenceId="1" sysUpTime="243"][timeQuality tzKnown="1" isSynced="0"][origin software="solid-syslog-example" swVersion="0.1.0" enterpriseId="32473" ip="10.0.2.15"] device started
-parsed PRIORITY=134 TIMESTAMP=2026-07-29T10:49:57+00:00 HOSTNAME=10.0.2.15 APP_NAME=solid-syslog-example PROCID= MSGID=BOOT STRUCTURED_DATA=[meta sequenceId="1" sysUpTime="243"][timeQuality tzKnown="1" isSynced="0"][origin software="solid-syslog-example" swVersion="0.1.0" enterpriseId="32473" ip="10.0.2.15"] MSG=device started
+wire   <134>1 2026-07-29T10:57:51.850000Z 10.0.2.15 solid-syslog-example - BOOT [meta sequenceId="1" sysUpTime="385"][timeQuality tzKnown="1" isSynced="0"][origin software="solid-syslog-example" swVersion="0.1.0" enterpriseId="32473" ip="10.0.2.15"][logPipeline@32473 transport="tls" atRest="hmac-sha256"] device started
+parsed PRIORITY=134 TIMESTAMP=2026-07-29T10:57:51+00:00 HOSTNAME=10.0.2.15 APP_NAME=solid-syslog-example PROCID= MSGID=BOOT STRUCTURED_DATA=[meta sequenceId="1" sysUpTime="385"][timeQuality tzKnown="1" isSynced="0"][origin software="solid-syslog-example" swVersion="0.1.0" enterpriseId="32473" ip="10.0.2.15"][logPipeline@32473 transport="tls" atRest="hmac-sha256"] MSG=device started
 ```
 
-## Self-check (vs measurements/hmac.csv)
+## Self-check (vs measurements/pipeline-sd.csv)
 
 ```text
-  OK    flash_text: 363088 (expected 363088, Δ0)
-  OK    flash_data: 644 (expected 644, Δ0)
+  OK    flash_text: 363208 (expected 363208, Δ0)
+  OK    flash_data: 648 (expected 648, Δ0)
   OK    static_bss: 146232 (expected 146232, Δ0)
   OK    heap_used: 4440 (expected 4440, Δ0)
   OK    mbedtls_peak: 36096 (expected 36096, Δ0)
   OK    mbedtls_free: 18176 (expected 18176, Δ0)
   OK    lwip_mem_free: 7576 (expected 7576, Δ0)
-  OK    lwip_pbufs_free: 13 (expected 13, Δ0)
+  OK    lwip_pbufs_free: 14 (expected 14, Δ0)
   OK    stack_log: 832 (expected 832, Δ0)
   OK    stack_service: 3852 (expected 3852, Δ0)
   OK    stack_harness: 2848 (expected 2848, Δ0)