Maximally minimal stack trace standardization

John Lenz concavelenz at gmail.com
Thu Mar 12 01:31:41 UTC 2015


I'll retract that suggestion having tried to write an argument for it.  It
sad though, removing "stack" isn't really an option.






On Wed, Mar 11, 2015 at 12:03 PM, Mark S. Miller <erights at google.com> wrote:

> I don't understand. Could you show example code? Thanks.
>
>
>
> On Wed, Mar 11, 2015 at 12:00 PM, John Lenz <concavelenz at gmail.com> wrote:
>
>>
>>
>> On Tue, Mar 10, 2015 at 9:10 PM, Mark S. Miller <erights at google.com>
>> wrote:
>>
>>> On Tue, Mar 10, 2015 at 9:02 PM, Domenic Denicola <d at domenic.me> wrote:
>>>
>>>>  I don’t see how any of this follows. SES can censor/remove/etc.
>>>> either the .stack getter or the .getStack function. They are isomorphic.
>>>>
>>>
>>> I can selectively provide or deny a given getStack function to different
>>> code in the same realm.
>>>
>>
>> Can't you do the same by hiding "Error" in the same way that "window" is
>> hidden?  Through a proxy or subclass?
>>
>>
>>>
>>>
>>>>
>>>>
>>>> .stack already has very close to de-facto standard behavior.
>>>>
>>>
>>> Have you looked at the case analysis I go through in debug.js to parse
>>> the variety of stack formats we currently have?
>>>
>>>
>>>
>>>> We should be attempting to converge it to a standard, and not leaving
>>>> it a non-interoperable mess while adding a second API.
>>>>
>>>>
>>>>
>>>> I also don’t see why .stack cannot map backward through different
>>>> source maps. Again, a getter and a function are isomorphic in this regard.
>>>>
>>>
>>> In a given realm, there can only be one Error.prototype.stack. But what
>>> getStack function is in scope can differ per scope as well as per loader.
>>>
>>>
>>>
>>>>
>>>>
>>>> *From:* Mark S. Miller [mailto:erights at google.com]
>>>> *Sent:* Wednesday, March 11, 2015 12:12
>>>> *To:* Domenic Denicola
>>>> *Cc:* John Lenz; es-discuss; Erik Arvidsson
>>>>
>>>> *Subject:* Re: Maximally minimal stack trace standardization
>>>>
>>>>
>>>>
>>>> No, that makes the std SES API non-conformant to the std API, making
>>>> porting more difficult, and making it harder to write code that works in
>>>> both environments.
>>>>
>>>>
>>>>
>>>> Also, if you make it look like err.stack, then no matter what you
>>>> stdize, it will conflict with existing err.stack behavior, since they
>>>> conflict with each other. This makes the transition more difficult. If the
>>>> new std behavior looks like getStack(err), then it can be rolled out
>>>> without creating a transition conflict.
>>>>
>>>>
>>>>
>>>> As so often happens, the better security is the better modularity. If
>>>> you make it err.stack, then you have to make visible one canonical mapping
>>>> to source positions. If you make it getStack(err), then different getStack
>>>> functions might map backwards through different sourcemaps.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Tue, Mar 10, 2015 at 7:45 PM, Domenic Denicola <d at domenic.me> wrote:
>>>>
>>>>  Can’t we just have Error.prototype.stack be a getter that SES is
>>>> allowed to delete and hide away for its own purposes later?
>>>>
>>>>
>>>>
>>>> *From:* es-discuss [mailto:es-discuss-bounces at mozilla.org] *On Behalf
>>>> Of *John Lenz
>>>> *Sent:* Wednesday, March 11, 2015 08:35
>>>> *To:* Mark S. Miller
>>>> *Cc:* es-discuss; Erik Arvidsson
>>>> *Subject:* Re: Maximally minimal stack trace standardization
>>>>
>>>>
>>>>
>>>>  Ok, as long as we are clear there is an existing information leak on
>>>> non-v8 engines.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Tue, Mar 10, 2015 at 1:48 PM, Mark S. Miller <erights at google.com>
>>>> wrote:
>>>>
>>>>  On Chrome and Opera (v8), <
>>>> https://code.google.com/p/google-caja/source/browse/trunk/src/com/google/caja/ses/debug.js>
>>>> hides the stack. It is important that we not lose this.
>>>>
>>>>
>>>>
>>>> Regarding the rest, as previously discussed, there are enough
>>>> differences between browsers that there is no legacy we must codify because
>>>> of web-wide agreement. Take a look at the extensive efforts <
>>>> https://code.google.com/p/google-caja/source/browse/trunk/src/com/google/caja/ses/debug.js>
>>>> makes to parse despite these differences in stack format. As long as we're
>>>> standardizing something not compat with web-wide legacy, as we must, we
>>>> might as well also fix this security leak in the process.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Tue, Mar 10, 2015 at 1:24 PM, John Lenz <concavelenz at gmail.com>
>>>> wrote:
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Mon, Mar 9, 2015 at 5:45 PM, Mark S. Miller <erights at google.com>
>>>> wrote:
>>>>
>>>>   On Mon, Mar 9, 2015 at 5:02 PM, John Lenz <concavelenz at gmail.com>
>>>> wrote:
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Mon, Mar 9, 2015 at 12:15 PM, Mark S. Miller <erights at google.com>
>>>> wrote:
>>>>
>>>>   On Sat, Mar 7, 2015 at 2:55 PM, John Lenz <concavelenz at gmail.com>
>>>> wrote:
>>>>
>>>>  I wanted to ping this thread and see how we could get "max-min stack
>>>> traces" to the next step?
>>>>
>>>>
>>>>
>>>> Hi John, the best way to take this to the next step is to read <
>>>> https://docs.google.com/document/d/1QbEE0BsO4lvl7NFTn5WXWeiEIBfaVUF7Dk0hpPpPDzU/edit>
>>>> and submit a proposal to <https://github.com/tc39/ecma262>.
>>>>
>>>>
>>>>
>>>> "If you are a TC39 member representative, just submit a pull request
>>>> for your proposal."
>>>>
>>>>
>>>>
>>>> Since you are at a member organization, attend and participate actively
>>>> at TC39 meetings to advance your proposal through the process.
>>>>
>>>>
>>>>
>>>> Please keep in mind that the stack trace information should not be
>>>> available simply from the error object by itself, as that is a bad
>>>> information leak.
>>>>
>>>>
>>>>
>>>> The threads I dug up, simply state what you state here.  That there is
>>>> an "information leak".  Are filename and function names considered
>>>> sensitive?  In what way?
>>>>
>>>>
>>>>
>>>> They reveal details of the callee's computation to the caller that the
>>>> callee should have been able to assume were private. See starting at middle
>>>> of 2nd paragraph of <
>>>> http://combex.com/papers/darpa-review/security-review.html#UniversalScope
>>>> >.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> the depth of the execution stack is visible, which could pose a risk in
>>>> certain scenarios: for instance, consider trusted code containing a
>>>> recursive function whose level of recursion depends on some sensitive data
>>>> (e.g., a secret cryptographic key), and suppose the recursive function is
>>>> called with arguments that induce it to hit an error condition and throw an
>>>> exception from deep within the recursion.  In such a case, the caller might
>>>> be able to learn something about the callee’s secrets by catching the
>>>> exception, examining the resulting stack trace, and recovering the stack
>>>> depth.  These scenarios do not occur in the DarpaBrowser, but have been
>>>> used in exploits on other systems.  Accordingly, though the risk for
>>>> DarpaBrowser is small, it should probably be repaired (Fixing this was
>>>> determined not to be hard).
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>     --David Wagner and E. Dean Tribble,
>>>>
>>>>         "A Security Review of the Combex DarpaBrowser Architecture"
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Likewise, the risk here -- of only a stack of function names and source
>>>> positions -- is small. But it violates the normal privacy assumptions
>>>> between caller and callee; and fixing it is again not hard -- via getStack.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>   I did not intend to promote a "rich stack inspection API" such as V8
>>>> has.
>>>>
>>>>
>>>>
>>>> That's good, but there is one thing I really like about the rich
>>>> inspection API that it would be a shame to lose: The user doesn't have to
>>>> do their own adhoc parsing of yet another ad hoc textual format. Since this
>>>> format contains function names, we would then even need to worry about
>>>> maliciously chosen function names, intended to get this stack format
>>>> parsing code to misparse. If the stack is a stack of, for example, JSON
>>>> strings, then we avoid this hazard.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Sure, but I feel like that is independent, I mostly want to codify what
>>>> already exists and standardize throw/rethrow behavior.   That is why I ask
>>>> about the information leak.  Error objects already have "stack" properties
>>>> on all the major browsers. If "stack" leaks information then they already
>>>> do and the rectification should be there. (It makes no sense to add a
>>>> "leak-free" API when a "leaky" one already exists).
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>>
>>>>     Cheers,
>>>>     --MarkM
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>>
>>>>     Cheers,
>>>>     --MarkM
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>>
>>>>     Cheers,
>>>>     --MarkM
>>>>
>>>
>>>
>>>
>>> --
>>>     Cheers,
>>>     --MarkM
>>>
>>
>>
>
>
> --
>     Cheers,
>     --MarkM
>
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