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Merge pull request #358 from github/external-control-file-path
Add rb/path-injection query
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‎ruby/change-notes/2021-10-20-path-injection.md

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lgtm,codescanning
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* A new query (`rb/path-injection`) has been added. The query finds file operations using paths that derive from user input without being sanitized.

‎ruby/ql/lib/codeql/ruby/Concepts.qll

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@@ -583,3 +583,21 @@ module OrmInstantiation {
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abstract predicate methodCallMayAccessField(string methodName);
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}
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}
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/** Provides classes for modeling path-related APIs. */
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module Path {
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/**
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* A data-flow node that performs path sanitization. This is often needed in order
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* to safely access paths.
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*/
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class PathSanitization extends DataFlow::Node instanceof PathSanitization::Range { }
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/** Provides a class for modeling new path sanitization APIs. */
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module PathSanitization {
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/**
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* A data-flow node that performs path sanitization. This is often needed in order
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* to safely access paths.
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*/
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abstract class Range extends DataFlow::Node { }
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}
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}

‎ruby/ql/lib/codeql/ruby/Frameworks.qll

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private import codeql.ruby.frameworks.ActionController
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private import codeql.ruby.frameworks.ActiveRecord
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private import codeql.ruby.frameworks.ActiveStorage
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private import codeql.ruby.frameworks.ActionView
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private import codeql.ruby.frameworks.StandardLibrary
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private import codeql.ruby.frameworks.Files

‎ruby/ql/lib/codeql/ruby/dataflow/FlowSummary.qll

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@@ -6,7 +6,9 @@ private import internal.FlowSummaryImpl as Impl
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private import internal.DataFlowDispatch
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// import all instances below
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private module Summaries { }
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private module Summaries {
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private import codeql.ruby.Frameworks
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}
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class SummaryComponent = Impl::Public::SummaryComponent;
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‎ruby/ql/lib/codeql/ruby/dataflow/internal/DataFlowPrivate.qll

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@@ -398,7 +398,7 @@ private module ParameterNodes {
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override DataFlowCallable getEnclosingCallable() { result = sc }
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override Location getLocationImpl() { none() }
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override EmptyLocation getLocationImpl() { any() }
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override string toStringImpl() { result = "parameter " + pos + " of " + sc }
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}
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override DataFlowCallable getEnclosingCallable() { result = c }
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override Location getLocationImpl() { none() }
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override EmptyLocation getLocationImpl() { any() }
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override string toStringImpl() { result = "[summary] " + state + " in " + c }
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}

‎ruby/ql/lib/codeql/ruby/dataflow/internal/FlowSummaryImplSpecific.qll

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@@ -64,6 +64,9 @@ predicate summaryElement(DataFlowCallable c, string input, string output, string
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SummaryComponent interpretComponentSpecific(string c) {
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c = "BlockArgument" and
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result = FlowSummary::SummaryComponent::block()
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or
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c = "Argument[_]" and
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result = FlowSummary::SummaryComponent::argument(any(int i | i >= 0))
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}
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/** Gets the return kind corresponding to specification `"ReturnValue"`. */

‎ruby/ql/lib/codeql/ruby/frameworks/ActiveStorage.qll

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private import codeql.ruby.AST
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private import codeql.ruby.ApiGraphs
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private import codeql.ruby.Concepts
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private import codeql.ruby.DataFlow
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private import codeql.ruby.dataflow.FlowSummary
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/** Defines calls to `ActiveStorage::Filename#sanitized` as path sanitizers. */
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class ActiveStorageFilenameSanitizedCall extends Path::PathSanitization::Range, DataFlow::CallNode {
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ActiveStorageFilenameSanitizedCall() {
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this.getReceiver() =
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API::getTopLevelMember("ActiveStorage").getMember("Filename").getAnInstantiation() and
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this.asExpr().getExpr().(MethodCall).getMethodName() = "sanitized"
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}
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}
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/** Taint summary for `ActiveStorage::Filename.new`. */
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class ActiveStorageFilenameNewSummary extends SummarizedCallable {
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ActiveStorageFilenameNewSummary() { this = "ActiveStorage::Filename.new" }
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override MethodCall getACall() {
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result =
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API::getTopLevelMember("ActiveStorage")
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.getMember("Filename")
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.getAnInstantiation()
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.asExpr()
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.getExpr()
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}
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override predicate propagatesFlowExt(string input, string output, boolean preservesValue) {
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input = "Argument[0]" and
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output = "ReturnValue" and
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preservesValue = false
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}
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}
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/** Taint summary for `ActiveStorage::Filename#sanitized`. */
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class ActiveStorageFilenameSanitizedSummary extends SummarizedCallable {
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ActiveStorageFilenameSanitizedSummary() { this = "ActiveStorage::Filename#sanitized" }
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override MethodCall getACall() {
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result =
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API::getTopLevelMember("ActiveStorage")
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.getMember("Filename")
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.getInstance()
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.getAMethodCall("sanitized")
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.asExpr()
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.getExpr()
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}
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override predicate propagatesFlowExt(string input, string output, boolean preservesValue) {
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input = "Argument[-1]" and
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output = "ReturnValue" and
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preservesValue = false
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}
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}

‎ruby/ql/lib/codeql/ruby/frameworks/Files.qll

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@@ -7,6 +7,7 @@ private import codeql.ruby.Concepts
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private import codeql.ruby.ApiGraphs
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private import codeql.ruby.DataFlow
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private import codeql.ruby.frameworks.StandardLibrary
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private import codeql.ruby.dataflow.FlowSummary
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private DataFlow::Node ioInstanceInstantiation() {
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result = API::getTopLevelMember("IO").getAnInstantiation() or
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override DataFlow::Node getAPermissionNode() { result = permissionArg }
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}
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/**
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* Flow summary for several methods on the `File` class that propagate taint
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* from their first argument to the return value.
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*/
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class FilePathConversionSummary extends SummarizedCallable {
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string methodName;
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FilePathConversionSummary() {
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methodName = ["absolute_path", "dirname", "expand_path", "path", "realdirpath", "realpath"] and
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this = "File." + methodName
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}
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override MethodCall getACall() {
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result = API::getTopLevelMember("File").getAMethodCall(methodName).asExpr().getExpr()
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}
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override predicate propagatesFlowExt(string input, string output, boolean preservesValue) {
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input = "Argument[0]" and
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output = "ReturnValue" and
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preservesValue = false
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}
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}
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/**
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* Flow summary for `File.join`, which propagates taint from every argument to
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* its return value.
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*/
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class FileJoinSummary extends SummarizedCallable {
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FileJoinSummary() { this = "File.join" }
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override MethodCall getACall() {
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result = API::getTopLevelMember("File").getAMethodCall("join").asExpr().getExpr()
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}
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override predicate propagatesFlowExt(string input, string output, boolean preservesValue) {
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input = "Argument[_]" and
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output = "ReturnValue" and
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preservesValue = false
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}
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}
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}
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/**

‎ruby/ql/lib/codeql/ruby/security/PathInjectionCustomizations.qll

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/**
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* Provides default sources, sinks and sanitizers for reasoning about
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* path injection vulnerabilities, as well as extension points for
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* adding your own.
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*/
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private import ruby
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private import codeql.ruby.ApiGraphs
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private import codeql.ruby.CFG
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private import codeql.ruby.Concepts
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private import codeql.ruby.DataFlow
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private import codeql.ruby.dataflow.BarrierGuards
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private import codeql.ruby.dataflow.RemoteFlowSources
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module PathInjection {
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/**
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* A data flow source for path injection vulnerabilities.
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*/
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abstract class Source extends DataFlow::Node { }
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/**
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* A data flow sink for path injection vulnerabilities.
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*/
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abstract class Sink extends DataFlow::Node { }
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/**
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* A sanitizer guard for path injection vulnerabilities.
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*/
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abstract class SanitizerGuard extends DataFlow::BarrierGuard { }
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/**
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* A source of remote user input, considered as a flow source.
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*/
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class RemoteFlowSourceAsSource extends Source, RemoteFlowSource { }
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/**
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* A file system access, considered as a flow sink.
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*/
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class FileSystemAccessAsSink extends Sink {
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FileSystemAccessAsSink() { this = any(FileSystemAccess e).getAPathArgument() }
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}
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/**
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* A comparison with a constant string, considered as a sanitizer-guard.
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*/
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class StringConstCompareAsSanitizerGuard extends SanitizerGuard, StringConstCompare { }
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/**
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* An inclusion check against an array of constant strings, considered as a
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* sanitizer-guard.
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*/
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class StringConstArrayInclusionCallAsSanitizerGuard extends SanitizerGuard,
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StringConstArrayInclusionCall { }
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}

‎ruby/ql/lib/codeql/ruby/security/PathInjectionQuery.qll

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/**
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* Provides a taint tracking configuration for reasoning about
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* path injection vulnerabilities.
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*
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* Note, for performance reasons: only import this file if
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* `PathInjection::Configuration` is needed, otherwise
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* `PathInjectionCustomizations` should be imported instead.
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*/
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import PathInjectionCustomizations
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private import codeql.ruby.Concepts
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private import codeql.ruby.DataFlow
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private import codeql.ruby.TaintTracking
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/**
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* A taint-tracking configuration for reasoning about path injection
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* vulnerabilities.
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*/
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class Configuration extends TaintTracking::Configuration {
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Configuration() { this = "PathInjection" }
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override predicate isSource(DataFlow::Node source) { source instanceof PathInjection::Source }
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override predicate isSink(DataFlow::Node sink) { sink instanceof PathInjection::Sink }
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override predicate isSanitizer(DataFlow::Node node) { node instanceof Path::PathSanitization }
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override predicate isSanitizerGuard(DataFlow::BarrierGuard guard) {
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guard instanceof PathInjection::SanitizerGuard
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}
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}

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