reachableBy() does not seem to be the solution because that does not find the data flow either:
joern> cpg.call.id(1000105L).reachableBy(cpg.call.id(1000105L)).l
res100: List[Call] = List(
Call(
id -> 1000105L,
code -> "x = source()",
name -> "<operator>.assignment",
order -> 2,
methodInstFullName -> None,
methodFullName -> "<operator>.assignment",
argumentIndex -> 2,
dispatchType -> "STATIC_DISPATCH",
signature -> "TODO assignment signature",
typeFullName -> "ANY",
dynamicTypeHintFullName -> List(),
lineNumber -> Some(3),
columnNumber -> Some(6),
resolved -> None,
depthFirstOrder -> None,
internalFlags -> None
)
)
joern> cpg.call.id(1000119L).reachableBy(cpg.call.id(1000119L)).l
res101: List[Call] = List(
Call(
id -> 1000119L,
code -> "sink(y)",
name -> "sink",
order -> 3,
methodInstFullName -> None,
methodFullName -> "sink",
argumentIndex -> 3,
dispatchType -> "STATIC_DISPATCH",
signature -> "TODO assignment signature",
typeFullName -> "ANY",
dynamicTypeHintFullName -> List(),
lineNumber -> Some(7),
columnNumber -> Some(3),
resolved -> None,
depthFirstOrder -> None,
internalFlags -> None
)
)
joern> cpg.call.id(1000105L).reachableBy(cpg.call.id(1000119L)).l
res102: List[Call] = List()
joern> cpg.call.id(1000119L).reachableBy(cpg.call.id(1000105L)).l
res103: List[Call] = List()i printed the reachability of the nodes to themselves first so you can be sure that i'm at the correct nodes. do you know why this doesn't work? :)
@FJuilia_twitter I am not 100% certain, but I think the behavior you're seeing is because when you're referencing the call to the assigment operator, you're actually referring to the return value of that call, which in your case, is not part of the flow.
if you'd take the source as being the identifier
if you'd take the source as being the identifier
x at line 3, you'd find a flow, and similarly for the call to source also at line 3
def source = cpg.identifier.lineNumber(3)
def sink = cpg.call.name("sink")
sink.reachableBy(source).l
@MeNicefellow it might be a better idea to export to the dot format: https://docs.joern.io/exporting/
Anyone got any idea how to get the line number corresponds to a cpg node?
When I use joern-export to export it to dot files.
@FJuilia_twitter it depends what you mean by gets written to. For assignments like
x = 2, you can search the graph for CALL nodes with the assignment operator as their method, e.g. cpg.call.methodFullName(Operators.assignment).l. If you're looking for byte-copying stdlib functions with a specific variable as argument, you would search for cpg.call.code(".*strcpy.*").where(_.argument.codeExact("x")) . Other steps from the reference card might be helpful https://docs.joern.io/cpgql/reference-card
@ursachec thanks for the ideas. i'm mostly concerned about writes through operators, not through functions that just happen to perform a write. but there are many ways operators can write. i can think of =, +=, -=, *=, /=, %=, |=, &=, ^=, <<=, >>=, var++, ++var, var--, and --var. but there might be more. i think that arrays and structs further complicate things. is there a universal way of detecting writes, at least as far as operators are concerned?
So you can think of the method "assigment". If i stick to the code in the screenshot, it is
=(res,crypto_scalarmult((unsigned char *)q, (unsigned char *)n, (unsigned char *)p).
you can find a list of the operators at: https://github.com/ShiftLeftSecurity/codepropertygraph/blob/master/schema/src/main/resources/schemas/operators.json
@itsacoderepo thanks but i know that operators are implemented as calls. i was wondering whether there is something built-in that finds all calls that definitely perform a write. shortly before you answered, i gave up on finding it and am now using a filter:
.filter(node => node.property("NAME") != null && (Array("<operator>.preIncrement", "<operator>.postIncrement", "<operator>.preDecrement", "<operator>.postDecrement").toList.contains(node.property("NAME").toString) || node.property("NAME").toString.slice(0, 21).equals("<operator>.assignment")))
you can use regex to get the methods you want ^
From there you can go to the calls:
joern> cpg.method.name("<operator>.*").callIn.head
res12: Call = Call(
id -> 1000882L,
code -> "--pos",
name -> "<operator>.preDecrement",
order -> 3,
methodInstFullName -> None,
methodFullName -> "<operator>.preDecrement",
argumentIndex -> 3,
dispatchType -> "STATIC_DISPATCH",
signature -> "TODO assignment signature",
typeFullName -> "ANY",
dynamicTypeHintFullName -> List(),
lineNumber -> Some(value = 189),
columnNumber -> Some(value = 26),
resolved -> None,
depthFirstOrder -> None,
internalFlags -> None
)
or
joern> val myOperators = List("<operator>.preDecrement", "<operator>.assignment")
myOperators: List[String] = List("<operator>.preDecrement", "<operator>.assignment")
joern> cpg.method.name(myOperators:_*).name.p
res18: List[String] = List("<operator>.preDecrement", "<operator>.assignment")
I personally like to create a list of interesting methods at the beginning of a script and use it as "var arg" later on, like
myOperators:_*
hi! I'm a starter of Joern, and I have difficulty connecting Joern server mode. (./joern --server).
I want to connect my VM server(Ubuntu) with my local pc(MacOs).
(I turn on the joern server in my vm server and try to access the server through python in local PC,MacOS)
But, when I ran my python program, the program failed due to a connection error.
Here are some of the details:
[ip info]
vmware ubuntu(NAT): 172.16.191.2
[error message]
File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.8/lib/python3.8/asyncio/selector_events.py", line 526, in _sock_connect_cb
raise OSError(err, f'Connect call failed {address}')
ConnectionRefusedError: [Errno 61] Connect call failed ('172.16.191.2', 8080)
[in my python program code]server_endpoint = "172.16.191.2:8080" //following github(cpgqls-client) example
[More info]
1) I checked vm netstat when I turned on Joern server, and I saw that port 8080 port is open.
2) I checked connection between vm and local PC, and it’s ok(checking through ping)
3) I checked tcpdump in local PC, when local PC access to VM Joern server Port, it returns RST packet, so the connection failed.
So… is there a solution about this issue?
Hi, I want to run a script to extract PDG/AST/CFG and save it to a JSON file by using Joern . I fine-tuning the "graph-for-funcs.sc" of the old version Joern, and it can work. But the result missing a lot of information compared to the result which extracting by Joern Shell Command (e.g. "cpg.method(xx).dotPdg.l").
val cfgChildren = method.out(EdgeTypes.CFG).asScala.collect { case node: nodes.CfgNode => node }.toList
// val local = new NodeSteps(
val local = new Traversal(
//methodVertex
method
.out(EdgeTypes.CONTAINS)
.hasLabel(NodeTypes.BLOCK)
.out(EdgeTypes.AST)
.hasLabel(NodeTypes.LOCAL)
.cast[nodes.Local])
val sink = local.evalType(".*").referencingIdentifiers.dedup
//val source = new NodeSteps(methodVertex.out(EdgeTypes.CONTAINS).hasLabel(NodeTypes.CALL).cast[nodes.Call]).nameNot("<operator>.*").dedup
val source = new Traversal(method.out(EdgeTypes.CONTAINS).hasLabel(NodeTypes.CALL).cast[nodes.Call]).nameNot("<operator>.*").dedup
val pdgChildren = sink
.reachableByFlows(source)
.l
.flatMap { path =>
path.elements
.map {
case trackingPoint @ (_: MethodParameterIn) => trackingPoint.start.method.head
case trackingPoint => trackingPoint.cfgNode
}
}
.filter(_.toString != methodId)
GraphForFuncsFunction(methodName, methodFile, methodId, astChildren, cfgChildren, pdgChildren.distinct)
i have the following snippet:
int
main(int argc, char *argv[]) {
int eaten = atoi(argv[1]);
int value ;
if (!strcmp(argv[1]), "drink") {
eaten += 1;
value = eaten * 3;
} else {
value = eaten;
}
return value;
}
i ran the following query:
cpg.returns.l(0).reachableByFlows(cpg.call("atoi")).l
to check the possible flows from atoi() to the return of the function
but the query only lists one path ("if " case flow)
and not the other ("else" case flow)
i expected it to list 2 flows (i.e 2 Paths)
is my query correct?
I tried running Joern on a toy C++ project with a class which has public and private members. However, while running a query to figure out whether the members are public or private, it just gives an empty List()