10_taint_tracking.ql

/**
 * @kind path-problem
 */

import cpp
import semmle.code.cpp.dataflow.TaintTracking
import DataFlow::PathGraph

class NetworkByteSwap extends Expr {
    NetworkByteSwap () {
        exists(MacroInvocation mi |
            mi.getMacroName().regexpMatch("ntoh(s|l|ll)") and
            this = mi.getExpr())
    }
}

class Config extends TaintTracking::Configuration {
  Config() { this = "NetworkToMemFuncLength" }

  override predicate isSource(DataFlow::Node source) {
    source.asExpr() instanceof NetworkByteSwap
  }
  override predicate isSink(DataFlow::Node sink) {
    exists(FunctionCall fc | fc.getTarget().getName() = "memcpy" and sink.asExpr() = fc.getArgument(2))
  }
}

from Config cfg, DataFlow::PathNode source, DataFlow::PathNode sink
where cfg.hasFlowPath(source, sink)
select sink, source, sink, "Network byte swap flows to memcpy"