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codeql/python/ql/test/experimental/meta/ConceptsTest.qll
Rasmus Wriedt Larsen 11cd0dbbc0 Python: Add concepts for public-key generation
I did spend some time to figure out how to best write `minimumSecureKeySize`
predicate. I wanted to write once and for all the recommended sizes for each
cryptosystem.

I considered making the predicate such as

```codeql
int minimumSecureKeySize() {
    this.getName() = "RSA" and result = 2048
    or
    this.getName() = "DSA" and result = 2048
    or
    this.getName() = "ECC" and result = 244
}
```

but then it would be impossible to add a new model without also being able to
modify the body of this predicate -- which seems like a bad way to start off a
brand new way of modeling things.

So I considered if we could add it to the non-range class, such as

```codeql
class RSAKeyGeneration extends KeyGeneration {
  RSAKeyGeneration() { this.getName() = "RSA" }

  override int minimumSecureKeySize() { result = 2048 }
}
```

This has the major problem that when you're writing the models for a new
API (and therefore extending KeyGeneration::Range), there is no way for you to
see that you need to take this extra step :| (also problem about how we should
define `minimumSecureKeySize` on `KeyGeneration` class then, since if we make it
abstract, we effectively disable the ability to refine `KeyGeneration` since any
subclass must provide an implementation.)

So, therefore I ended up with this solution ;)
2021-02-19 13:59:16 +01:00

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import python
import semmle.python.dataflow.new.DataFlow
import semmle.python.Concepts
import TestUtilities.InlineExpectationsTest
string value_from_expr(Expr e) {
// TODO: This one is starting to look like `repr` predicate from TestTaintLib
result =
e.(StrConst).getPrefix() + e.(StrConst).getText() +
e.(StrConst).getPrefix().regexpReplaceAll("[a-zA-Z]+", "")
or
result = e.(Name).getId()
or
not e instanceof StrConst and
not e instanceof Name and
result = e.toString()
}
class SystemCommandExecutionTest extends InlineExpectationsTest {
SystemCommandExecutionTest() { this = "SystemCommandExecutionTest" }
override string getARelevantTag() { result = "getCommand" }
override predicate hasActualResult(Location location, string element, string tag, string value) {
exists(location.getFile().getRelativePath()) and
exists(SystemCommandExecution sce, DataFlow::Node command |
command = sce.getCommand() and
location = command.getLocation() and
element = command.toString() and
value = value_from_expr(command.asExpr()) and
tag = "getCommand"
)
}
}
class DecodingTest extends InlineExpectationsTest {
DecodingTest() { this = "DecodingTest" }
override string getARelevantTag() {
result in ["decodeInput", "decodeOutput", "decodeFormat", "decodeMayExecuteInput"]
}
override predicate hasActualResult(Location location, string element, string tag, string value) {
exists(location.getFile().getRelativePath()) and
exists(Decoding d |
exists(DataFlow::Node data |
location = data.getLocation() and
element = data.toString() and
value = value_from_expr(data.asExpr()) and
(
data = d.getAnInput() and
tag = "decodeInput"
or
data = d.getOutput() and
tag = "decodeOutput"
)
)
or
exists(string format |
location = d.getLocation() and
element = format and
value = format and
format = d.getFormat() and
tag = "decodeFormat"
)
or
d.mayExecuteInput() and
location = d.getLocation() and
element = d.toString() and
value = "" and
tag = "decodeMayExecuteInput"
)
}
}
class EncodingTest extends InlineExpectationsTest {
EncodingTest() { this = "EncodingTest" }
override string getARelevantTag() { result in ["encodeInput", "encodeOutput", "encodeFormat"] }
override predicate hasActualResult(Location location, string element, string tag, string value) {
exists(location.getFile().getRelativePath()) and
exists(Encoding e |
exists(DataFlow::Node data |
location = data.getLocation() and
element = data.toString() and
value = value_from_expr(data.asExpr()) and
(
data = e.getAnInput() and
tag = "encodeInput"
or
data = e.getOutput() and
tag = "encodeOutput"
)
)
or
exists(string format |
location = e.getLocation() and
element = format and
value = format and
format = e.getFormat() and
tag = "encodeFormat"
)
)
}
}
class CodeExecutionTest extends InlineExpectationsTest {
CodeExecutionTest() { this = "CodeExecutionTest" }
override string getARelevantTag() { result = "getCode" }
override predicate hasActualResult(Location location, string element, string tag, string value) {
exists(location.getFile().getRelativePath()) and
exists(CodeExecution ce, DataFlow::Node code |
exists(location.getFile().getRelativePath()) and
code = ce.getCode() and
location = code.getLocation() and
element = code.toString() and
value = value_from_expr(code.asExpr()) and
tag = "getCode"
)
}
}
class SqlExecutionTest extends InlineExpectationsTest {
SqlExecutionTest() { this = "SqlExecutionTest" }
override string getARelevantTag() { result = "getSql" }
override predicate hasActualResult(Location location, string element, string tag, string value) {
exists(location.getFile().getRelativePath()) and
exists(SqlExecution e, DataFlow::Node sql |
exists(location.getFile().getRelativePath()) and
sql = e.getSql() and
location = e.getLocation() and
element = sql.toString() and
value = value_from_expr(sql.asExpr()) and
tag = "getSql"
)
}
}
class HttpServerRouteSetupTest extends InlineExpectationsTest {
HttpServerRouteSetupTest() { this = "HttpServerRouteSetupTest" }
override string getARelevantTag() { result in ["routeSetup"] }
override predicate hasActualResult(Location location, string element, string tag, string value) {
exists(location.getFile().getRelativePath()) and
exists(HTTP::Server::RouteSetup setup |
location = setup.getLocation() and
element = setup.toString() and
(
value = "\"" + setup.getUrlPattern() + "\""
or
not exists(setup.getUrlPattern()) and
value = ""
) and
tag = "routeSetup"
)
}
}
class HttpServerRequestHandlerTest extends InlineExpectationsTest {
HttpServerRequestHandlerTest() { this = "HttpServerRequestHandlerTest" }
override string getARelevantTag() { result in ["requestHandler", "routedParameter"] }
override predicate hasActualResult(Location location, string element, string tag, string value) {
exists(location.getFile().getRelativePath()) and
(
exists(HTTP::Server::RequestHandler handler |
location = handler.getLocation() and
element = handler.toString() and
value = "" and
tag = "requestHandler"
)
or
exists(HTTP::Server::RequestHandler handler, Parameter param |
param = handler.getARoutedParameter() and
location = param.getLocation() and
element = param.toString() and
value = param.asName().getId() and
tag = "routedParameter"
)
)
}
}
class HttpServerHttpResponseTest extends InlineExpectationsTest {
File file;
HttpServerHttpResponseTest() {
file.getExtension() = "py" and
this = "HttpServerHttpResponseTest: " + file
}
override string getARelevantTag() { result in ["HttpResponse", "responseBody", "mimetype"] }
override predicate hasActualResult(Location location, string element, string tag, string value) {
// By adding `file` as a class field, and these two restrictions, it's possible to
// say that we only want to check _some_ tags for certain files. This helped make
// flask tests more readable since adding full annotations for HttpResponses in the
// the tests for routing setup is both annoying and not very useful.
location.getFile() = file and
exists(file.getRelativePath()) and
// we need to do this step since we expect subclasses could override getARelevantTag
tag = getARelevantTag() and
(
exists(HTTP::Server::HttpResponse response |
location = response.getLocation() and
element = response.toString() and
value = "" and
tag = "HttpResponse"
)
or
exists(HTTP::Server::HttpResponse response |
location = response.getLocation() and
element = response.toString() and
value = value_from_expr(response.getBody().asExpr()) and
tag = "responseBody"
)
or
exists(HTTP::Server::HttpResponse response |
location = response.getLocation() and
element = response.toString() and
// Ensure that an expectation value such as "mimetype=text/html; charset=utf-8" is parsed as a
// single expectation with tag mimetype, and not as two expecations with tags mimetype and
// charset.
(
if exists(response.getMimetype().indexOf(" "))
then value = "\"" + response.getMimetype() + "\""
else value = response.getMimetype()
) and
tag = "mimetype"
)
)
}
}
class HttpServerHttpRedirectResponseTest extends InlineExpectationsTest {
HttpServerHttpRedirectResponseTest() { this = "HttpServerHttpRedirectResponseTest" }
override string getARelevantTag() { result in ["HttpRedirectResponse", "redirectLocation"] }
override predicate hasActualResult(Location location, string element, string tag, string value) {
exists(location.getFile().getRelativePath()) and
(
exists(HTTP::Server::HttpRedirectResponse redirect |
location = redirect.getLocation() and
element = redirect.toString() and
value = "" and
tag = "HttpRedirectResponse"
)
or
exists(HTTP::Server::HttpRedirectResponse redirect |
location = redirect.getLocation() and
element = redirect.toString() and
value = value_from_expr(redirect.getRedirectLocation().asExpr()) and
tag = "redirectLocation"
)
)
}
}
class FileSystemAccessTest extends InlineExpectationsTest {
FileSystemAccessTest() { this = "FileSystemAccessTest" }
override string getARelevantTag() { result = "getAPathArgument" }
override predicate hasActualResult(Location location, string element, string tag, string value) {
exists(location.getFile().getRelativePath()) and
exists(FileSystemAccess a, DataFlow::Node path |
path = a.getAPathArgument() and
location = a.getLocation() and
element = path.toString() and
value = value_from_expr(path.asExpr()) and
tag = "getAPathArgument"
)
}
}
class PathNormalizationTest extends InlineExpectationsTest {
PathNormalizationTest() { this = "PathNormalizationTest" }
override string getARelevantTag() { result = "pathNormalization" }
override predicate hasActualResult(Location location, string element, string tag, string value) {
exists(location.getFile().getRelativePath()) and
exists(Path::PathNormalization n |
location = n.getLocation() and
element = n.toString() and
value = "" and
tag = "pathNormalization"
)
}
}
class SafeAccessCheckTest extends InlineExpectationsTest {
SafeAccessCheckTest() { this = "SafeAccessCheckTest" }
override string getARelevantTag() { result in ["checks", "branch"] }
override predicate hasActualResult(Location location, string element, string tag, string value) {
exists(location.getFile().getRelativePath()) and
exists(Path::SafeAccessCheck c, DataFlow::Node checks, boolean branch |
c.checks(checks.asCfgNode(), branch) and
location = c.getLocation() and
(
element = checks.toString() and
value = value_from_expr(checks.asExpr()) and
tag = "checks"
or
element = branch.toString() and
value = branch.toString() and
tag = "branch"
)
)
}
}
class PublicKeyGenerationTest extends InlineExpectationsTest {
PublicKeyGenerationTest() { this = "PublicKeyGenerationTest" }
override string getARelevantTag() { result in ["PublicKeyGeneration", "keySize"] }
override predicate hasActualResult(Location location, string element, string tag, string value) {
exists(location.getFile().getRelativePath()) and
exists(Cryptography::PublicKey::KeyGeneration keyGen |
location = keyGen.getLocation() and
(
element = keyGen.toString() and
value = "" and
tag = "PublicKeyGeneration"
or
element = keyGen.toString() and
value = keyGen.getKeySizeWithOrigin(_).toString() and
tag = "keySize"
)
)
}
}