Summary:
In Java, we handle unknown code by propagating behavior from the parameters of the unknown function call to the return value (or constructed object, in the case of a constructor). But we do this in a somewhat silly way--generating a new summary with these semantics at each unknown call site. Instead, this diff introduces these two options as predefined behaviors and adds specialized code for them.
As a side effect of this approach, unknown functions are no longer counted as passthroughs. This is ok; the original behavior was less of a reasoned decision and more of an unintended consequence of the way we decided to handle unknown code.
This new approach ought to be more efficient than the old one, and as a virtuous side effect it will be easier to specify how to handle unknown code in other languages like C++.
Reviewed By: jeremydubreil
Differential Revision: D4205624
fbshipit-source-id: bf97445
Summary:
Let's introduce some concepts. A "known unknown" function is one for which no Java code exists (e.g., `native`, `abstract`, and `interface methods`). An "unknown unknown" function is one for which Java code may or may not exist, but we don't have the code or we choose not to analyze it (e.g., non-modeled methods from the core Java or Android libraries).
Previously, Quandary handled both known unknowns and unknown unknowns by propagating taint from the parameters of the unknown function to its return value. It turns out that it is really expensive to do this for known unknown functions. D4142697 was the diff that starting handling known unknown functions in this way, and bisecting shows that it was the start of the recent performance problems for Quandary.
This diff essentially reverts D4142697 by handling known unknowns as skips instead. Pragmatically, doing the propagation trick for Java/Android library functions (e.g., `String` functions!) matters much more, so i'm not too worried about the missed behaviors from this. Ideally, we will go back to the old handling once performance has improved (have lots of ideas there). But I need this to unblock me in the meantime.
Reviewed By: jeremydubreil
Differential Revision: D4205507
fbshipit-source-id: 79cb9c8
Summary: Generalizing jvillard's awesome work to include passthroughs in traces, then calling it from Quandary.
Reviewed By: jvillard
Differential Revision: D4172108
fbshipit-source-id: 0296c59
Summary:
There's not really a concept of callee here, so s/callee/callsite/, and "to"
suggests we get the callee whereas we update it, so s/to/with/.
Feel free to bikeshed further.
Reviewed By: sblackshear
Differential Revision: D4153426
fbshipit-source-id: 6ea762c
Summary: If a procedure is both a source and a sink for the same value, and it's a sink first, you will get a false positive when applying the summary for the procedure.
Reviewed By: cristianoc
Differential Revision: D4145246
fbshipit-source-id: 97f0022
Summary:
Analyses should handle methods whose code is unknown and methods whose summary is a no-op differently.
Previously, this was done correctly for some kinds of methods (e.g., native methods, which were recognized as unknown), but not for others (interface and abstract methods).
This diff makes sure we correctly treat all three kinds as unknown.
Reviewed By: jeremydubreil
Differential Revision: D4142697
fbshipit-source-id: c88cff3
Summary:
Our default strategy for handling unknown code is to propagate taint from the actuals to the return value.
But for commonly-used methods like `StringBuilder.append` (used every time you do `+` with a string in Java), this doesn't work.
The taint should be propagated to both the receiver and the return value in these cases.
I'm considering a solution where we always propagate taint to the receiver of unknown functions in the future, but I am concerned about the performance.
So let's stick with a few special string cases for now.
Reviewed By: cristianoc
Differential Revision: D4124355
fbshipit-source-id: 5b2a232
Summary: Other checkers are going to start using these, so they shouldn't live in the Quandary directory anymore
Reviewed By: jvillard
Differential Revision: D4124654
fbshipit-source-id: b1d5bdd
Summary: A must-have for reporting taint errors and any other interprocedural error where the trace is sufficiently complex.
Reviewed By: jvillard
Differential Revision: D4124072
fbshipit-source-id: 26b3b2b
Summary: Other checkers are going to start using these, so they shouldn't live in the Quandary directory anymore
Reviewed By: jvillard
Differential Revision: D4117359
fbshipit-source-id: e3f151e
Summary: A must-have for reporting taint errors and any other interprocedural error where the trace is sufficiently complex.
Reviewed By: jvillard
Differential Revision: D4106352
fbshipit-source-id: b2677e6
Summary:
Previously, we recorded direct sinks as sinks and transitive sinks as passthroughs. This makes it difficult to create an expanded interprocedural trace when recording an error because we can't distinguish between sinks (which we want to expand) and passthroughs (which we don't). This diff changes recording of sinks so that a sink is now the *last* function in a trace to call a sink. To find out what the original sink was, the summary for the transitive sink in the trace will now need to be (recursively) expanded until we bottom out in the original sink.
Will do the same for sources in a follow-up diff.
Reviewed By: cristianoc
Differential Revision: D4103759
fbshipit-source-id: 6f435f5
Summary:
See code comment about `throw exn` being translated as `return exn`.
This problem was revealed by D4081279, which started grabbing access paths from exceptions.
Reviewed By: jvillard
Differential Revision: D4096391
fbshipit-source-id: 9d91513
Summary:
this makes frontends no longer depend on SymExec.ml. `ModelBuiltins` was split into two modules:
- `BuiltinDecl` with procnames for builtins (used to determine whether some function is a builtin)
- `BuiltinDefn` with implementations used by `SymExec`
- they both have similar type defined in `BUILTINS.S` which makes sure that new builtin gets added into both modules.
During the refactor I ran some scripts:
`BuiltinDecl.ml`:
let X = create_procname "X"
cat BuiltinDecl.ml | grep "create_procname" | tail -70 | awk ' { print $1,$2,$3,$4,"\42"$2"\42"} '
then manually confirm string match. Exceptions:
"__exit" -> "_exit"
"objc_cpp_throw" -> "__infer_objc_cpp_throw"
__objc_dictionary_literal
nsArray_arrayWithObjects
nsArray_arrayWithObjectsCount
`BuiltinDefn.ml`:
let X = Builtin.register BuiltinDecl.X execute_X
cat BuiltinDecl.ml | grep "create_procname" | tail -70 | awk ' { print $1,$2,$3,"Builtin.register BuiltinDecl."$2,"execute_"$2} '
then, fix all compilation problems
Reviewed By: jberdine
Differential Revision: D3951035
fbshipit-source-id: f059602
Summary:
Right now, taint gets lost if it flows into a constructor or procedure whose implementation is missing.
Since the core Java (e.g., String) and Android classes (e.g, Intent) are among these, this is bad.
We could handle this by writing a bunch of models instead, but that would be a lot of work (plus we may still miss cases).
Reviewed By: jvillard
Differential Revision: D4051591
fbshipit-source-id: 65851c8
Summary:
Before, if I wrote code like
```
x = src()
sink(x)
sink(x)
```
we would report three times instead of two.
The first flow would be double-reported.
Reviewed By: jeremydubreil
Differential Revision: D4024678
fbshipit-source-id: fcd5b30
Summary:
We were previously leaking the passthroughs of the callee into the caller.
We definitely don't want to do this since it could make the summaries higher up in the call stack explode.
If we need to know the passthroughs of a callee, we can always read them from the callee's summary.
Reviewed By: jeremydubreil
Differential Revision: D3972679
fbshipit-source-id: 5b5903f
Summary:
Change Sil.Call instruction to have only a single optional return
identifier, insted of a list. Essentially none of the code handled
multiple return identifiers. Also, add the type of the return
identitifier to Call instructions.
Reviewed By: sblackshear
Differential Revision: D3919358
fbshipit-source-id: d2d4f72
Summary: The Infer builtins can be used in the e2e tests, but those tests should not depend on the Infer models to avoid cyclic dependencies. This diff separates the models and the Infer builtins in two directories so that the test can depend on the builtins without depending on the models
Reviewed By: sblackshear
Differential Revision: D3929478
fbshipit-source-id: 7d0ab79
Summary:
The global reference `DB.current_source` is used internally in the module DB, by all the front-ends, and directly and indirectly by the back-end, including saving and restoring the state in case of on-demand procedure calls. In particular, it is heavily used in printing functions.
This diff cleans up the flow of information about what the current file is, making it explicit, and removes the reference.
Reviewed By: jberdine
Differential Revision: D3901247
fbshipit-source-id: ef596bd
Summary:
This diff removes the redundancy in the representation of types where
struct types could be represented either directly using Tstruct or
indirectly using Tvar to refer to the type environment. A consequence
is that it is much harder to construct large type values.
Reviewed By: sblackshear, cristianoc
Differential Revision: D3839753
fbshipit-source-id: cf04ea5