Merge pull request github#11627 from jketema/getaddrinfo

C++: Model `getaddrinfo` as flow source

Author: MathiasVP

cpp/ql/lib/change-notes/2022-12-08-support-getaddrinfo-dataflow.md

@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* The `getaddrinfo` function is now recognized as a flow source.

cpp/ql/lib/semmle/code/cpp/models/implementations/Inet.qll

@@ -1,9 +1,10 @@
 import semmle.code.cpp.models.interfaces.Taint
 import semmle.code.cpp.models.interfaces.Alias
 import semmle.code.cpp.models.interfaces.ArrayFunction
+import semmle.code.cpp.models.interfaces.FlowSource
 
 private class InetNtoa extends TaintFunction {
-  InetNtoa() { hasGlobalName("inet_ntoa") }
+  InetNtoa() { this.hasGlobalName("inet_ntoa") }
 
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     input.isParameter(0) and
@@ -12,7 +13,7 @@ private class InetNtoa extends TaintFunction {
 }
 
 private class InetAton extends TaintFunction, ArrayFunction {
-  InetAton() { hasGlobalName("inet_aton") }
+  InetAton() { this.hasGlobalName("inet_aton") }
 
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     input.isParameterDeref(0) and
@@ -32,7 +33,7 @@ private class InetAton extends TaintFunction, ArrayFunction {
 }
 
 private class InetAddr extends TaintFunction, ArrayFunction, AliasFunction {
-  InetAddr() { hasGlobalName("inet_addr") }
+  InetAddr() { this.hasGlobalName("inet_addr") }
 
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     input.isParameterDeref(0) and
@@ -51,7 +52,7 @@ private class InetAddr extends TaintFunction, ArrayFunction, AliasFunction {
 }
 
 private class InetNetwork extends TaintFunction, ArrayFunction {
-  InetNetwork() { hasGlobalName("inet_network") }
+  InetNetwork() { this.hasGlobalName("inet_network") }
 
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     input.isParameterDeref(0) and
@@ -64,7 +65,7 @@ private class InetNetwork extends TaintFunction, ArrayFunction {
 }
 
 private class InetMakeaddr extends TaintFunction {
-  InetMakeaddr() { hasGlobalName("inet_makeaddr") }
+  InetMakeaddr() { this.hasGlobalName("inet_makeaddr") }
 
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     (
@@ -76,7 +77,7 @@ private class InetMakeaddr extends TaintFunction {
 }
 
 private class InetLnaof extends TaintFunction {
-  InetLnaof() { hasGlobalName("inet_lnaof") }
+  InetLnaof() { this.hasGlobalName("inet_lnaof") }
 
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     input.isParameter(0) and
@@ -85,7 +86,7 @@ private class InetLnaof extends TaintFunction {
 }
 
 private class InetNetof extends TaintFunction {
-  InetNetof() { hasGlobalName("inet_netof") }
+  InetNetof() { this.hasGlobalName("inet_netof") }
 
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     input.isParameter(0) and
@@ -94,7 +95,7 @@ private class InetNetof extends TaintFunction {
 }
 
 private class InetPton extends TaintFunction, ArrayFunction {
-  InetPton() { hasGlobalName("inet_pton") }
+  InetPton() { this.hasGlobalName("inet_pton") }
 
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     (
@@ -114,7 +115,7 @@ private class InetPton extends TaintFunction, ArrayFunction {
 }
 
 private class Gethostbyname extends TaintFunction, ArrayFunction {
-  Gethostbyname() { hasGlobalName("gethostbyname") }
+  Gethostbyname() { this.hasGlobalName("gethostbyname") }
 
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     input.isParameterDeref(0) and
@@ -127,7 +128,7 @@ private class Gethostbyname extends TaintFunction, ArrayFunction {
 }
 
 private class Gethostbyaddr extends TaintFunction, ArrayFunction {
-  Gethostbyaddr() { hasGlobalName("gethostbyaddr") }
+  Gethostbyaddr() { this.hasGlobalName("gethostbyaddr") }
 
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     (
@@ -142,3 +143,21 @@ private class Gethostbyaddr extends TaintFunction, ArrayFunction {
 
   override predicate hasArrayWithNullTerminator(int bufParam) { bufParam = 0 }
 }
+
+private class Getaddrinfo extends TaintFunction, ArrayFunction, RemoteFlowSourceFunction {
+  Getaddrinfo() { this.hasGlobalName("getaddrinfo") }
+
+  override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+    input.isParameterDeref([0 .. 2]) and
+    output.isParameterDeref(3)
+  }
+
+  override predicate hasArrayInput(int bufParam) { bufParam in [0, 1] }
+
+  override predicate hasArrayWithNullTerminator(int bufParam) { bufParam in [0, 1] }
+
+  override predicate hasRemoteFlowSource(FunctionOutput output, string description) {
+    output.isParameterDeref(3) and
+    description = "Address returned by " + this.getName()
+  }
+}

cpp/ql/test/library-tests/dataflow/source-sink-tests/sources-and-sinks.cpp

@@ -40,3 +40,13 @@ void test_scanf(FILE *stream, int *d, char *buf) {
   scanf("%d %s", d, buf); // $ local_source=40:18 local_source=40:21
   fscanf(stream, "%d %s", d, buf);  // $ remote_source=41:27 remote_source=41:30
 }
+
+struct addrinfo;
+
+int getaddrinfo(const char *hostname, const char *servname,
+                const struct addrinfo *hints, struct addrinfo **res);
+
+void test_inet(char *hostname, char *servname, struct addrinfo *hints) {
+  addrinfo *res;
+  int ret = getaddrinfo(hostname, servname, hints, &res); // $ remote_source
+}