Maximally minimal stack trace standardization

Mark S. Miller erights at google.com
Wed Mar 11 04:10:47 UTC 2015


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.


>
>
> .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
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