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C++: Remove CP in cpp/command-line-injection #10123

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Merged
jketema merged 1 commit into from
Aug 22, 2022
Merged

C++: Remove CP in cpp/command-line-injection #10123

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31 changes: 29 additions & 2 deletions cpp/ql/src/Security/CWE/CWE-078/ExecTainted.ql
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ import semmle.code.cpp.security.Security
import semmle.code.cpp.valuenumbering.GlobalValueNumbering
import semmle.code.cpp.ir.IR
import semmle.code.cpp.ir.dataflow.TaintTracking
import semmle.code.cpp.ir.dataflow.TaintTracking2
import semmle.code.cpp.security.FlowSources
import semmle.code.cpp.models.implementations.Strcat
import DataFlow::PathGraph
Expand Down Expand Up @@ -83,6 +84,32 @@ class ExecState extends DataFlow::FlowState {
DataFlow::Node getFstNode() { result = fst }

DataFlow::Node getSndNode() { result = snd }

/** Holds if this is a possible `ExecState` for `sink`. */
predicate isFeasibleForSink(DataFlow::Node sink) {
any(ExecStateConfiguration conf).hasFlow(snd, sink)
}
}

/**
* A `TaintTracking` configuration that's used to find the relevant `ExecState`s for a
* given sink. This avoids a cartesian product between all sinks and all `ExecState`s in
* `ExecTaintConfiguration::isSink`.
*/
class ExecStateConfiguration extends TaintTracking2::Configuration {
ExecStateConfiguration() { this = "ExecStateConfiguration" }

override predicate isSource(DataFlow::Node source) {
exists(ExecState state | state.getSndNode() = source)
}

override predicate isSink(DataFlow::Node sink) {
shellCommand(sinkAsArgumentIndirection(sink), _)
}

override predicate isSanitizerOut(DataFlow::Node node) {
isSink(node, _) // Prevent duplicates along a call chain, since `shellCommand` will include wrappers
}
}

class ExecTaintConfiguration extends TaintTracking::Configuration {
Expand All @@ -94,8 +121,8 @@ class ExecTaintConfiguration extends TaintTracking::Configuration {
}

override predicate isSink(DataFlow::Node sink, DataFlow::FlowState state) {
shellCommand(sinkAsArgumentIndirection(sink), _) and
state instanceof ExecState
any(ExecStateConfiguration conf).isSink(sink) and
state.(ExecState).isFeasibleForSink(sink)
}

override predicate isAdditionalTaintStep(
Expand Down