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codeql/python/ql/lib/semmle/python/security/dataflow/LogInjectionCustomizations.qll

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/**
* Provides default sources, sinks and sanitizers for detecting
* "log injection"
* vulnerabilities, as well as extension points for adding your own.
*/
private import python
private import semmle.python.dataflow.new.DataFlow
private import semmle.python.Concepts
private import semmle.python.dataflow.new.RemoteFlowSources
private import semmle.python.dataflow.new.BarrierGuards
/**
* Provides default sources, sinks and sanitizers for detecting
* "log injection"
* vulnerabilities, as well as extension points for adding your own.
*/
module LogInjection {
/**
* A data flow source for "log injection" vulnerabilities.
*/
abstract class Source extends DataFlow::Node { }
/**
* A data flow sink for "log injection" vulnerabilities.
*/
abstract class Sink extends DataFlow::Node { }
/**
* A sanitizer for "log injection" vulnerabilities.
*/
abstract class Sanitizer extends DataFlow::Node { }
/**
* A source of remote user input, considered as a flow source.
*/
class RemoteFlowSourceAsSource extends Source, RemoteFlowSource { }
/**
* A logging operation, considered as a flow sink.
*/
class LoggingAsSink extends Sink {
LoggingAsSink() {
this = any(Logging write).getAnInput() and
// since the inner implementation of the `logging.Logger.warn` function is
// ```py
// class Logger:
// def warn(self, msg, *args, **kwargs):
// warnings.warn("The 'warn' method is deprecated, "
// "use 'warning' instead", DeprecationWarning, 2)
// self.warning(msg, *args, **kwargs)
// ```
// any time we would report flow to such a logging sink, we can ALSO report
// the flow to the `self.warning` sink -- obviously we don't want that.
//
// However, simply removing taint edges out of a sink is not a good enough solution,
// since we would only flag one of the `logging.info` calls in the following example
// due to use-use flow
// ```py
// logger.warn(user_controlled)
// logger.warn(user_controlled)
// ```
//
// The same approach is used in the command injection query.
not exists(Module loggingInit |
loggingInit.getName() = "logging.__init__" and
this.getScope().getEnclosingModule() = loggingInit and
// do allow this call if we're analyzing logging/__init__.py as part of CPython though
not exists(loggingInit.getFile().getRelativePath())
)
}
}
/**
* A comparison with a constant string, considered as a sanitizer-guard.
*/
class StringConstCompareAsSanitizerGuard extends Sanitizer, StringConstCompareBarrier { }
/**
* A call to replace line breaks, considered as a sanitizer.
*/
class ReplaceLineBreaksSanitizer extends Sanitizer, DataFlow::CallCfgNode {
// Note: This sanitizer is not 100% accurate, since:
// - we do not check that all kinds of line breaks are replaced
// - we do not check that one kind of line breaks is not replaced by another
//
// However, we lack a simple way to do better, and the query would likely
// be too noisy without this.
//
// TODO: Consider rewriting using flow states.
ReplaceLineBreaksSanitizer() {
this.getFunction().(DataFlow::AttrRead).getAttributeName() = "replace" and
this.getArg(0).asExpr().(StrConst).getText() in ["\r\n", "\n"]
}
}
}