Add support to generate_stack action (#4382)

* Stack trace collection configuration

* Collect and report stack trace for appsec events

* Handle generate_stack waf action

* Fix linting in config.spec.js

* Add assertion for stack trace tag in meta_struct for express test

* Refactor reportStackTrace and some additional test

* Fix lint

* Additional assert in reportStackTrace test

* Update config

* Rework on stack trace collection

* Callsite line and column as numbers

* Update packages/dd-trace/src/appsec/stack_trace.js

Co-authored-by: Ugaitz Urien <ugaitz.urien@datadoghq.com>

* Update packages/dd-trace/src/appsec/stack_trace.js

Co-authored-by: Ugaitz Urien <ugaitz.urien@datadoghq.com>

* Reorder test structure

* Fix linting

* No exploit stack limit when max is set to 0 or below

* Fix filtered and capped frames case

* Fix lint

---------

Co-authored-by: Ugaitz Urien <ugaitz.urien@datadoghq.com>

docs/test.ts

@@ -119,6 +119,11 @@ tracer.init({
     },
     rasp: {
       enabled: true
+    },
+    stackTrace: {
+      enabled: true,
+      maxStackTraces: 5,
+      maxDepth: 42
     }
   }
 });

index.d.ts

@@ -700,6 +700,25 @@ declare namespace tracer {
          * @default false
          */
         enabled?: boolean
+      },
+      /**
+       * Configuration for stack trace reporting
+       */
+      stackTrace?: {
+        /** Whether to enable stack trace reporting.
+         * @default true
+         */
+        enabled?: boolean,
+
+        /** Specifies the maximum number of stack traces to be reported.
+         * @default 2
+         */
+        maxStackTraces?: number,
+
+        /** Specifies the maximum depth of a stack trace to be reported.
+         * @default 32
+         */
+        maxDepth?: number,
       }
     };
 

packages/dd-trace/src/appsec/iast/path-line.js

@@ -3,6 +3,7 @@
 const path = require('path')
 const process = require('process')
 const { calculateDDBasePath } = require('../../util')
+const { getCallSiteList } = require('../stack_trace')
 const pathLine = {
   getFirstNonDDPathAndLine,
   getNodeModulesPaths,
@@ -24,24 +25,6 @@ const EXCLUDED_PATH_PREFIXES = [
   'async_hooks'
 ]
 
-function getCallSiteInfo () {
-  const previousPrepareStackTrace = Error.prepareStackTrace
-  const previousStackTraceLimit = Error.stackTraceLimit
-  let callsiteList
-  Error.stackTraceLimit = 100
-  try {
-    Error.prepareStackTrace = function (_, callsites) {
-      callsiteList = callsites
-    }
-    const e = new Error()
-    e.stack
-  } finally {
-    Error.prepareStackTrace = previousPrepareStackTrace
-    Error.stackTraceLimit = previousStackTraceLimit
-  }
-  return callsiteList
-}
-
 function getFirstNonDDPathAndLineFromCallsites (callsites, externallyExcludedPaths) {
   if (callsites) {
     for (let i = 0; i < callsites.length; i++) {
@@ -91,7 +74,7 @@ function isExcluded (callsite, externallyExcludedPaths) {
 }
 
 function getFirstNonDDPathAndLine (externallyExcludedPaths) {
-  return getFirstNonDDPathAndLineFromCallsites(getCallSiteInfo(), externallyExcludedPaths)
+  return getFirstNonDDPathAndLineFromCallsites(getCallSiteList(), externallyExcludedPaths)
 }
 
 function getNodeModulesPaths (...paths) {

packages/dd-trace/src/appsec/index.js

@@ -40,7 +40,7 @@ function enable (_config) {
     graphql.enable()
 
     if (_config.appsec.rasp.enabled) {
-      rasp.enable()
+      rasp.enable(_config)
     }
 
     setTemplates(_config)

packages/dd-trace/src/appsec/rasp.js

@@ -1,15 +1,20 @@
 'use strict'
 
 const { storage } = require('../../../datadog-core')
+const web = require('./../plugins/util/web')
 const addresses = require('./addresses')
 const { httpClientRequestStart } = require('./channels')
+const { reportStackTrace } = require('./stack_trace')
 const waf = require('./waf')
 
 const RULE_TYPES = {
   SSRF: 'ssrf'
 }
 
-function enable () {
+let config
+
+function enable (_config) {
+  config = _config
   httpClientRequestStart.subscribe(analyzeSsrf)
 }
 
@@ -28,12 +33,30 @@ function analyzeSsrf (ctx) {
     [addresses.HTTP_OUTGOING_URL]: url
   }
   // TODO: Currently this is only monitoring, we should
-  //     block the request if SSRF attempt and
-  //     generate stack traces
-  waf.run({ persistent }, req, RULE_TYPES.SSRF)
+  //     block the request if SSRF attempt
+  const result = waf.run({ persistent }, req, RULE_TYPES.SSRF)
+  handleResult(result, req)
+}
+
+function getGenerateStackTraceAction (actions) {
+  return actions?.generate_stack
+}
+
+function handleResult (actions, req) {
+  const generateStackTraceAction = getGenerateStackTraceAction(actions)
+  if (generateStackTraceAction && config.appsec.stackTrace.enabled) {
+    const rootSpan = web.root(req)
+    reportStackTrace(
+      rootSpan,
+      generateStackTraceAction.stack_id,
+      config.appsec.stackTrace.maxDepth,
+      config.appsec.stackTrace.maxStackTraces
+    )
+  }
 }
 
 module.exports = {
   enable,
-  disable
+  disable,
+  handleResult
 }

packages/dd-trace/src/appsec/stack_trace.js

@@ -0,0 +1,91 @@
+'use strict'
+
+const { calculateDDBasePath } = require('../util')
+
+const ddBasePath = calculateDDBasePath(__dirname)
+
+const LIBRARY_FRAMES_BUFFER = 20
+
+function getCallSiteList (maxDepth = 100) {
+  const previousPrepareStackTrace = Error.prepareStackTrace
+  const previousStackTraceLimit = Error.stackTraceLimit
+  let callsiteList
+  Error.stackTraceLimit = maxDepth
+
+  try {
+    Error.prepareStackTrace = function (_, callsites) {
+      callsiteList = callsites
+    }
+    const e = new Error()
+    e.stack
+  } finally {
+    Error.prepareStackTrace = previousPrepareStackTrace
+    Error.stackTraceLimit = previousStackTraceLimit
+  }
+
+  return callsiteList
+}
+
+function filterOutFramesFromLibrary (callSiteList) {
+  return callSiteList.filter(callSite => !callSite.getFileName().includes(ddBasePath))
+}
+
+function getFramesForMetaStruct (callSiteList, maxDepth = 32) {
+  const maxCallSite = maxDepth < 1 ? Infinity : maxDepth
+
+  const filteredFrames = filterOutFramesFromLibrary(callSiteList)
+
+  const half = filteredFrames.length > maxCallSite ? Math.round(maxCallSite / 2) : Infinity
+
+  const indexedFrames = []
+  for (let i = 0; i < Math.min(filteredFrames.length, maxCallSite); i++) {
+    const index = i < half ? i : i + filteredFrames.length - maxCallSite
+    const callSite = filteredFrames[index]
+    indexedFrames.push({
+      id: index,
+      file: callSite.getFileName(),
+      line: callSite.getLineNumber(),
+      column: callSite.getColumnNumber(),
+      function: callSite.getFunctionName(),
+      class_name: callSite.getTypeName()
+    })
+  }
+
+  return indexedFrames
+}
+
+function reportStackTrace (rootSpan, stackId, maxDepth, maxStackTraces, callSiteListGetter = getCallSiteList) {
+  if (!rootSpan) return
+
+  if (!rootSpan.meta_struct) {
+    rootSpan.meta_struct = {}
+  }
+
+  if (!rootSpan.meta_struct['_dd.stack']) {
+    rootSpan.meta_struct['_dd.stack'] = {}
+  }
+
+  if (!rootSpan.meta_struct['_dd.stack'].exploit) {
+    rootSpan.meta_struct['_dd.stack'].exploit = []
+  }
+
+  if (maxStackTraces < 1 || rootSpan.meta_struct['_dd.stack'].exploit.length < maxStackTraces) {
+    // Since some frames will be discarded because they come from tracer codebase, a buffer is added
+    // to the limit in order to get as close as `maxDepth` number of frames.
+    const stackTraceLimit = maxDepth < 1 ? Infinity : maxDepth + LIBRARY_FRAMES_BUFFER
+    const callSiteList = callSiteListGetter(stackTraceLimit)
+    const frames = getFramesForMetaStruct(callSiteList, maxDepth)
+
+    rootSpan.meta_struct['_dd.stack'].exploit.push({
+      id: stackId,
+      language: 'nodejs',
+      frames
+    })
+  }
+}
+
+module.exports = {
+  getCallSiteList,
+  filterOutFramesFromLibrary,
+  reportStackTrace
+}

packages/dd-trace/src/config.js

@@ -440,6 +440,9 @@ class Config {
     this._setValue(defaults, 'appsec.rateLimit', 100)
     this._setValue(defaults, 'appsec.rules', undefined)
     this._setValue(defaults, 'appsec.sca.enabled', null)
+    this._setValue(defaults, 'appsec.stackTrace.enabled', true)
+    this._setValue(defaults, 'appsec.stackTrace.maxDepth', 32)
+    this._setValue(defaults, 'appsec.stackTrace.maxStackTraces', 2)
     this._setValue(defaults, 'appsec.wafTimeout', 5e3) // µs
     this._setValue(defaults, 'clientIpEnabled', false)
     this._setValue(defaults, 'clientIpHeader', null)
@@ -524,10 +527,13 @@ class Config {
       DD_APPSEC_ENABLED,
       DD_APPSEC_HTTP_BLOCKED_TEMPLATE_HTML,
       DD_APPSEC_HTTP_BLOCKED_TEMPLATE_JSON,
+      DD_APPSEC_MAX_STACK_TRACES,
+      DD_APPSEC_MAX_STACK_TRACE_DEPTH,
       DD_APPSEC_OBFUSCATION_PARAMETER_KEY_REGEXP,
       DD_APPSEC_OBFUSCATION_PARAMETER_VALUE_REGEXP,
       DD_APPSEC_RULES,
       DD_APPSEC_SCA_ENABLED,
+      DD_APPSEC_STACK_TRACE_ENABLED,
       DD_APPSEC_RASP_ENABLED,
       DD_APPSEC_TRACE_RATE_LIMIT,
       DD_APPSEC_WAF_TIMEOUT,
@@ -627,6 +633,11 @@ class Config {
     this._setString(env, 'appsec.rules', DD_APPSEC_RULES)
     // DD_APPSEC_SCA_ENABLED is never used locally, but only sent to the backend
     this._setBoolean(env, 'appsec.sca.enabled', DD_APPSEC_SCA_ENABLED)
+    this._setBoolean(env, 'appsec.stackTrace.enabled', DD_APPSEC_STACK_TRACE_ENABLED)
+    this._setValue(env, 'appsec.stackTrace.maxDepth', maybeInt(DD_APPSEC_MAX_STACK_TRACE_DEPTH))
+    this._envUnprocessed['appsec.stackTrace.maxDepth'] = DD_APPSEC_MAX_STACK_TRACE_DEPTH
+    this._setValue(env, 'appsec.stackTrace.maxStackTraces', maybeInt(DD_APPSEC_MAX_STACK_TRACES))
+    this._envUnprocessed['appsec.stackTrace.maxStackTraces'] = DD_APPSEC_MAX_STACK_TRACES
     this._setValue(env, 'appsec.wafTimeout', maybeInt(DD_APPSEC_WAF_TIMEOUT))
     this._envUnprocessed['appsec.wafTimeout'] = DD_APPSEC_WAF_TIMEOUT
     this._setBoolean(env, 'clientIpEnabled', DD_TRACE_CLIENT_IP_ENABLED)
@@ -767,6 +778,11 @@ class Config {
     this._setValue(opts, 'appsec.rateLimit', maybeInt(options.appsec.rateLimit))
     this._optsUnprocessed['appsec.rateLimit'] = options.appsec.rateLimit
     this._setString(opts, 'appsec.rules', options.appsec.rules)
+    this._setBoolean(opts, 'appsec.stackTrace.enabled', options.appsec.stackTrace?.enabled)
+    this._setValue(opts, 'appsec.stackTrace.maxDepth', maybeInt(options.appsec.stackTrace?.maxDepth))
+    this._optsUnprocessed['appsec.stackTrace.maxDepth'] = options.appsec.stackTrace?.maxDepth
+    this._setValue(opts, 'appsec.stackTrace.maxStackTraces', maybeInt(options.appsec.stackTrace?.maxStackTraces))
+    this._optsUnprocessed['appsec.stackTrace.maxStackTraces'] = options.appsec.stackTrace?.maxStackTraces
     this._setValue(opts, 'appsec.wafTimeout', maybeInt(options.appsec.wafTimeout))
     this._optsUnprocessed['appsec.wafTimeout'] = options.appsec.wafTimeout
     this._setBoolean(opts, 'clientIpEnabled', options.clientIpEnabled)

packages/dd-trace/src/format.js

@@ -53,6 +53,7 @@ function formatSpan (span) {
     resource: String(spanContext._name),
     error: 0,
     meta: {},
+    meta_struct: span.meta_struct,
     metrics: {},
     start: Math.round(span._startTime * 1e6),
     duration: Math.round(span._duration * 1e6),

packages/dd-trace/test/appsec/index.spec.js

@@ -200,7 +200,7 @@ describe('AppSec Index', () => {
     it('should call rasp enable', () => {
       AppSec.enable(config)
 
-      expect(rasp.enable).to.be.calledOnceWithExactly()
+      expect(rasp.enable).to.be.calledOnceWithExactly(config)
     })
 
     it('should not call rasp enable when rasp is disabled', () => {

packages/dd-trace/test/appsec/rasp.express.plugin.spec.js

@@ -74,6 +74,7 @@ withVersions('express', 'express', expressVersion => {
             await agent.use((traces) => {
               const span = getWebSpan(traces)
               assert.notProperty(span.meta, '_dd.appsec.json')
+              assert.notProperty(span.meta_struct || {}, '_dd.stack')
             })
           })
 
@@ -92,6 +93,7 @@ withVersions('express', 'express', expressVersion => {
               assert.equal(span.metrics['_dd.appsec.rasp.rule.eval'], 1)
               assert(span.metrics['_dd.appsec.rasp.duration'] > 0)
               assert(span.metrics['_dd.appsec.rasp.duration_ext'] > 0)
+              assert.property(span.meta_struct, '_dd.stack')
             })
           })
 
@@ -113,6 +115,7 @@ withVersions('express', 'express', expressVersion => {
               assert.equal(span.metrics['_dd.appsec.rasp.rule.eval'], 1)
               assert(span.metrics['_dd.appsec.rasp.duration'] > 0)
               assert(span.metrics['_dd.appsec.rasp.duration_ext'] > 0)
+              assert.property(span.meta_struct, '_dd.stack')
             })
           })
         })