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Python: dataflow, bypass ssa nodes #4657

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5153637
Python: bypass ssa nodes
yoff Nov 10, 2020
c5b2b06
Python: slight reformulation
yoff Nov 10, 2020
9d2633a
Python: update test expectations
yoff Nov 11, 2020
c3fdc7d
Python: Route defintion flow through defining node
yoff Nov 12, 2020
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7 changes: 7 additions & 0 deletions python/ql/src/semmle/python/Flow.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -661,6 +661,8 @@ class DefinitionNode extends ControlFlowNode {
exists(Assign a | list_or_tuple_nested_element(a.getATarget()).getAFlowNode() = this)
or
exists(For for | for.getTarget().getAFlowNode() = this)
or
exists(With with | with.getOptionalVars().getAFlowNode() = this)
}

/** flow node corresponding to the value assigned for the definition corresponding to this flow node */
Expand Down Expand Up @@ -791,6 +793,11 @@ private AstNode assigned_value(Expr lhs) {
or
/* for lhs in seq: => `result` is the `for` node, representing the `iter(next(seq))` operation. */
result.(For).getTarget() = lhs
or
exists(With with |
result = with.getContextExpr() and
lhs = with.getOptionalVars()
)
}

predicate nested_sequence_assign(
Expand Down
47 changes: 31 additions & 16 deletions python/ql/src/semmle/python/dataflow/new/internal/DataFlowPrivate.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -97,9 +97,9 @@ class SyntheticPostUpdateNode extends PostUpdateNode, TSyntheticPostUpdateNode {
}

/**
* Calls to constructors are treated as post-update nodes for the synthesized argument
* Calls to constructors act as post-update nodes for the synthesized argument
* that is mapped to the `self` parameter. That way, constructor calls represent the value of the
* object after the constructor (currently only `__init__`) has run.
* object _after_ the constructor (currently only `__init__`) has run.
*/
class ObjectCreationNode extends PostUpdateNode, NeedsSyntheticPreUpdateNode, CfgNode {
ObjectCreationNode() { node.(CallNode) = any(ClassCall c).getNode() }
Expand All @@ -122,33 +122,48 @@ module EssaFlow {
// Definition
// `x = f(42)`
// nodeFrom is `f(42)`, cfg node
// nodeTo is `x`, essa var
nodeFrom.(CfgNode).getNode() =
nodeTo.(EssaNode).getVar().getDefinition().(AssignmentDefinition).getValue()
// nodeTo `x`, cfg node
exists(EssaNodeDefinition ed, DefinitionNode def | def = ed.getDefiningNode() |
nodeFrom.asCfgNode() = def.getValue() and
nodeTo.asCfgNode() = def
)
or
// With definition
// `with f(42) as x:`
// Definition
// `x = f(42)`
// nodeFrom is `f(42)`, cfg node
// nodeTo is `x`, essa var
exists(With with, ControlFlowNode contextManager, ControlFlowNode var |
nodeFrom.(CfgNode).getNode() = contextManager and
nodeTo.(EssaNode).getVar().getDefinition().(WithDefinition).getDefiningNode() = var and
// see `with_flow` in `python/ql/src/semmle/python/dataflow/Implementation.qll`
with.getContextExpr() = contextManager.getNode() and
with.getOptionalVars() = var.getNode() and
contextManager.strictlyDominates(var)
// nodeTo is
// - `x`, essa var, if `x` is global
// - first use of `x`, cfg node, if `x` is not global
//
// case where `x` is not global
exists(EssaNodeDefinition ed |
nodeFrom.asCfgNode() = ed.getDefiningNode() and
defToFirstUse(ed.getVariable(), nodeTo.asCfgNode()) and
not ed.getVariable() instanceof GlobalSsaVariable
)
or
// case where `x` is global
exists(EssaNodeDefinition ed |
nodeFrom.asCfgNode() = ed.getDefiningNode() and
nodeTo.asVar() = ed.getVariable().(GlobalSsaVariable)
)
or
// Parameter definition
// `f(x)`
// nodeFrom is `x`, cfg node
// nodeTo is first use of `x`, cfg node
exists(ParameterDefinition pd |
nodeFrom.asCfgNode() = pd.getDefiningNode() and
nodeTo.asVar() = pd.getVariable()
defToFirstUse(pd.getVariable(), nodeTo.asCfgNode())
)
or
// First use after definition
// `y = 42`
// `x = f(y)`
// nodeFrom is `y` on first line, essa var
// nodeTo is `y` on second line, cfg node
//
// This case is now only used for captured variables.
defToFirstUse(nodeFrom.asVar(), nodeTo.asCfgNode())
or
// Next use after use
Expand Down
69 changes: 51 additions & 18 deletions python/ql/test/experimental/dataflow/basic/global.expected
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Original file line number Diff line number Diff line change
@@ -1,69 +1,102 @@
| test.py:1:1:1:21 | ControlFlowNode for FunctionExpr | test.py:1:5:1:17 | ControlFlowNode for obfuscated_id |
| test.py:1:1:1:21 | ControlFlowNode for FunctionExpr | test.py:1:5:1:17 | GSSA Variable obfuscated_id |
| test.py:1:1:1:21 | ControlFlowNode for FunctionExpr | test.py:7:5:7:17 | ControlFlowNode for obfuscated_id |
| test.py:1:5:1:17 | ControlFlowNode for obfuscated_id | test.py:1:5:1:17 | GSSA Variable obfuscated_id |
| test.py:1:5:1:17 | ControlFlowNode for obfuscated_id | test.py:7:5:7:17 | ControlFlowNode for obfuscated_id |
| test.py:1:5:1:17 | GSSA Variable obfuscated_id | test.py:7:5:7:17 | ControlFlowNode for obfuscated_id |
| test.py:1:19:1:19 | ControlFlowNode for x | test.py:1:19:1:19 | SSA variable x |
| test.py:1:19:1:19 | ControlFlowNode for x | test.py:2:3:2:3 | SSA variable y |
| test.py:1:19:1:19 | ControlFlowNode for x | test.py:2:3:2:3 | ControlFlowNode for y |
| test.py:1:19:1:19 | ControlFlowNode for x | test.py:2:7:2:7 | ControlFlowNode for x |
| test.py:1:19:1:19 | ControlFlowNode for x | test.py:3:3:3:3 | SSA variable z |
| test.py:1:19:1:19 | ControlFlowNode for x | test.py:3:3:3:3 | ControlFlowNode for z |
| test.py:1:19:1:19 | ControlFlowNode for x | test.py:3:7:3:7 | ControlFlowNode for y |
| test.py:1:19:1:19 | ControlFlowNode for x | test.py:4:10:4:10 | ControlFlowNode for z |
| test.py:1:19:1:19 | ControlFlowNode for x | test.py:7:1:7:1 | ControlFlowNode for b |
| test.py:1:19:1:19 | ControlFlowNode for x | test.py:7:1:7:1 | GSSA Variable b |
| test.py:1:19:1:19 | ControlFlowNode for x | test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() |
| test.py:1:19:1:19 | SSA variable x | test.py:2:3:2:3 | SSA variable y |
| test.py:1:19:1:19 | SSA variable x | test.py:2:3:2:3 | ControlFlowNode for y |
| test.py:1:19:1:19 | SSA variable x | test.py:2:7:2:7 | ControlFlowNode for x |
| test.py:1:19:1:19 | SSA variable x | test.py:3:3:3:3 | SSA variable z |
| test.py:1:19:1:19 | SSA variable x | test.py:3:3:3:3 | ControlFlowNode for z |
| test.py:1:19:1:19 | SSA variable x | test.py:3:7:3:7 | ControlFlowNode for y |
| test.py:1:19:1:19 | SSA variable x | test.py:4:10:4:10 | ControlFlowNode for z |
| test.py:1:19:1:19 | SSA variable x | test.py:7:1:7:1 | ControlFlowNode for b |
| test.py:1:19:1:19 | SSA variable x | test.py:7:1:7:1 | GSSA Variable b |
| test.py:1:19:1:19 | SSA variable x | test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() |
| test.py:2:3:2:3 | SSA variable y | test.py:3:3:3:3 | SSA variable z |
| test.py:2:3:2:3 | ControlFlowNode for y | test.py:3:3:3:3 | ControlFlowNode for z |
| test.py:2:3:2:3 | ControlFlowNode for y | test.py:3:7:3:7 | ControlFlowNode for y |
| test.py:2:3:2:3 | ControlFlowNode for y | test.py:4:10:4:10 | ControlFlowNode for z |
| test.py:2:3:2:3 | ControlFlowNode for y | test.py:7:1:7:1 | ControlFlowNode for b |
| test.py:2:3:2:3 | ControlFlowNode for y | test.py:7:1:7:1 | GSSA Variable b |
| test.py:2:3:2:3 | ControlFlowNode for y | test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() |
| test.py:2:3:2:3 | SSA variable y | test.py:3:3:3:3 | ControlFlowNode for z |
| test.py:2:3:2:3 | SSA variable y | test.py:3:7:3:7 | ControlFlowNode for y |
| test.py:2:3:2:3 | SSA variable y | test.py:4:10:4:10 | ControlFlowNode for z |
| test.py:2:3:2:3 | SSA variable y | test.py:7:1:7:1 | ControlFlowNode for b |
| test.py:2:3:2:3 | SSA variable y | test.py:7:1:7:1 | GSSA Variable b |
| test.py:2:3:2:3 | SSA variable y | test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() |
| test.py:2:7:2:7 | ControlFlowNode for x | test.py:2:3:2:3 | SSA variable y |
| test.py:2:7:2:7 | ControlFlowNode for x | test.py:3:3:3:3 | SSA variable z |
| test.py:2:7:2:7 | ControlFlowNode for x | test.py:2:3:2:3 | ControlFlowNode for y |
| test.py:2:7:2:7 | ControlFlowNode for x | test.py:3:3:3:3 | ControlFlowNode for z |
| test.py:2:7:2:7 | ControlFlowNode for x | test.py:3:7:3:7 | ControlFlowNode for y |
| test.py:2:7:2:7 | ControlFlowNode for x | test.py:4:10:4:10 | ControlFlowNode for z |
| test.py:2:7:2:7 | ControlFlowNode for x | test.py:7:1:7:1 | ControlFlowNode for b |
| test.py:2:7:2:7 | ControlFlowNode for x | test.py:7:1:7:1 | GSSA Variable b |
| test.py:2:7:2:7 | ControlFlowNode for x | test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() |
| test.py:3:3:3:3 | ControlFlowNode for z | test.py:4:10:4:10 | ControlFlowNode for z |
| test.py:3:3:3:3 | ControlFlowNode for z | test.py:7:1:7:1 | ControlFlowNode for b |
| test.py:3:3:3:3 | ControlFlowNode for z | test.py:7:1:7:1 | GSSA Variable b |
| test.py:3:3:3:3 | ControlFlowNode for z | test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() |
| test.py:3:3:3:3 | SSA variable z | test.py:4:10:4:10 | ControlFlowNode for z |
| test.py:3:3:3:3 | SSA variable z | test.py:7:1:7:1 | ControlFlowNode for b |
| test.py:3:3:3:3 | SSA variable z | test.py:7:1:7:1 | GSSA Variable b |
| test.py:3:3:3:3 | SSA variable z | test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() |
| test.py:3:7:3:7 | ControlFlowNode for y | test.py:3:3:3:3 | SSA variable z |
| test.py:3:7:3:7 | ControlFlowNode for y | test.py:3:3:3:3 | ControlFlowNode for z |
| test.py:3:7:3:7 | ControlFlowNode for y | test.py:4:10:4:10 | ControlFlowNode for z |
| test.py:3:7:3:7 | ControlFlowNode for y | test.py:7:1:7:1 | ControlFlowNode for b |
| test.py:3:7:3:7 | ControlFlowNode for y | test.py:7:1:7:1 | GSSA Variable b |
| test.py:3:7:3:7 | ControlFlowNode for y | test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() |
| test.py:4:10:4:10 | ControlFlowNode for z | test.py:7:1:7:1 | ControlFlowNode for b |
| test.py:4:10:4:10 | ControlFlowNode for z | test.py:7:1:7:1 | GSSA Variable b |
| test.py:4:10:4:10 | ControlFlowNode for z | test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() |
| test.py:6:1:6:1 | ControlFlowNode for a | test.py:1:19:1:19 | ControlFlowNode for x |
| test.py:6:1:6:1 | ControlFlowNode for a | test.py:2:3:2:3 | ControlFlowNode for y |
| test.py:6:1:6:1 | ControlFlowNode for a | test.py:2:7:2:7 | ControlFlowNode for x |
| test.py:6:1:6:1 | ControlFlowNode for a | test.py:3:3:3:3 | ControlFlowNode for z |
| test.py:6:1:6:1 | ControlFlowNode for a | test.py:3:7:3:7 | ControlFlowNode for y |
| test.py:6:1:6:1 | ControlFlowNode for a | test.py:4:10:4:10 | ControlFlowNode for z |
| test.py:6:1:6:1 | ControlFlowNode for a | test.py:6:1:6:1 | GSSA Variable a |
| test.py:6:1:6:1 | ControlFlowNode for a | test.py:7:1:7:1 | ControlFlowNode for b |
| test.py:6:1:6:1 | ControlFlowNode for a | test.py:7:1:7:1 | GSSA Variable b |
| test.py:6:1:6:1 | ControlFlowNode for a | test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() |
| test.py:6:1:6:1 | ControlFlowNode for a | test.py:7:19:7:19 | ControlFlowNode for a |
| test.py:6:1:6:1 | GSSA Variable a | test.py:1:19:1:19 | ControlFlowNode for x |
| test.py:6:1:6:1 | GSSA Variable a | test.py:1:19:1:19 | SSA variable x |
| test.py:6:1:6:1 | GSSA Variable a | test.py:2:3:2:3 | SSA variable y |
| test.py:6:1:6:1 | GSSA Variable a | test.py:2:3:2:3 | ControlFlowNode for y |
| test.py:6:1:6:1 | GSSA Variable a | test.py:2:7:2:7 | ControlFlowNode for x |
| test.py:6:1:6:1 | GSSA Variable a | test.py:3:3:3:3 | SSA variable z |
| test.py:6:1:6:1 | GSSA Variable a | test.py:3:3:3:3 | ControlFlowNode for z |
| test.py:6:1:6:1 | GSSA Variable a | test.py:3:7:3:7 | ControlFlowNode for y |
| test.py:6:1:6:1 | GSSA Variable a | test.py:4:10:4:10 | ControlFlowNode for z |
| test.py:6:1:6:1 | GSSA Variable a | test.py:7:1:7:1 | ControlFlowNode for b |
| test.py:6:1:6:1 | GSSA Variable a | test.py:7:1:7:1 | GSSA Variable b |
| test.py:6:1:6:1 | GSSA Variable a | test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() |
| test.py:6:1:6:1 | GSSA Variable a | test.py:7:19:7:19 | ControlFlowNode for a |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:1:19:1:19 | ControlFlowNode for x |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:1:19:1:19 | SSA variable x |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:2:3:2:3 | SSA variable y |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:2:3:2:3 | ControlFlowNode for y |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:2:7:2:7 | ControlFlowNode for x |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:3:3:3:3 | SSA variable z |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:3:3:3:3 | ControlFlowNode for z |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:3:7:3:7 | ControlFlowNode for y |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:4:10:4:10 | ControlFlowNode for z |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:6:1:6:1 | ControlFlowNode for a |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:6:1:6:1 | GSSA Variable a |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:7:1:7:1 | ControlFlowNode for b |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:7:1:7:1 | GSSA Variable b |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() |
| test.py:6:5:6:6 | ControlFlowNode for IntegerLiteral | test.py:7:19:7:19 | ControlFlowNode for a |
| test.py:7:1:7:1 | ControlFlowNode for b | test.py:7:1:7:1 | GSSA Variable b |
| test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() | test.py:7:1:7:1 | ControlFlowNode for b |
| test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() | test.py:7:1:7:1 | GSSA Variable b |
| test.py:7:19:7:19 | ControlFlowNode for a | test.py:1:19:1:19 | ControlFlowNode for x |
| test.py:7:19:7:19 | ControlFlowNode for a | test.py:1:19:1:19 | SSA variable x |
| test.py:7:19:7:19 | ControlFlowNode for a | test.py:2:3:2:3 | SSA variable y |
| test.py:7:19:7:19 | ControlFlowNode for a | test.py:2:3:2:3 | ControlFlowNode for y |
| test.py:7:19:7:19 | ControlFlowNode for a | test.py:2:7:2:7 | ControlFlowNode for x |
| test.py:7:19:7:19 | ControlFlowNode for a | test.py:3:3:3:3 | SSA variable z |
| test.py:7:19:7:19 | ControlFlowNode for a | test.py:3:3:3:3 | ControlFlowNode for z |
| test.py:7:19:7:19 | ControlFlowNode for a | test.py:3:7:3:7 | ControlFlowNode for y |
| test.py:7:19:7:19 | ControlFlowNode for a | test.py:4:10:4:10 | ControlFlowNode for z |
| test.py:7:19:7:19 | ControlFlowNode for a | test.py:7:1:7:1 | ControlFlowNode for b |
| test.py:7:19:7:19 | ControlFlowNode for a | test.py:7:1:7:1 | GSSA Variable b |
| test.py:7:19:7:19 | ControlFlowNode for a | test.py:7:5:7:20 | ControlFlowNode for obfuscated_id() |
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