On 21/07/2020 06:51, William A Rowe Jr wrote:
On Mon, Jul 20, 2020, 10:24 Ruediger Pluem <rpl...@apache.org
<mailto:rpl...@apache.org>> wrote:
On 7/20/20 4:45 PM, Yann Ylavic wrote:
> On Thu, Jul 16, 2020 at 10:31 PM Eric Covener <cove...@gmail.com
<mailto:cove...@gmail.com>> wrote:
>>
>> On Thu, Jul 16, 2020 at 3:31 PM Ruediger Pluem
<rpl...@apache.org <mailto:rpl...@apache.org>> wrote:
>>>
>>>
>>>
>>> On 6/24/20 1:27 PM, Eric Covener wrote:
>>>>>
>>>>> ProxyMappingDecoded is not needed anymore (and was removed).
>>>>> The mapping= tells mod_proxy at which stage ([pre_]translate) it
>>>>> should map the request path.
>>>> +1
>>>>
>>>
>>> Getting back to an old topic. Shouldn't we have a directive
similar to
>>> AllowEncodedSlashes that allows us to block URI's that contain
>>> URL fragments like /.; and /..; in order to avoid that someone
plays
>>> silly games that bypass Location settings and RewriteRules
>>> that might be used with a servlet engine in the backend? Happy
>>> to have that set to a default that allows /.; and /..;.
>>
>> +, but I'd want the safer default.
>
> Is this something we should care about outside the proxy
mapping=servlet case?
> In the other cases, "/.;" and "/..;" are nothing but plain text (they
> won't be treated as "/." and "/.." on the filesystem AFAICT), so we
> could let them 404 normally.
I think for the default handler this is no problem. As you state
such URL's likely produce just a 404 and we are done.
> In the mapping=servlet case, servlet normalization is applied to
> r->[parsed_]uri (no "/.;" or "/..;" anymore), so Location/..
matchings
> use the same uri-path than the backend.
But only if you have an appropriate ProxyPass in place. With
RewriteRules this does not work.
Hence I think we need an additional mechanism to handle this in case
of no ProxyPass directives.
I still fail to see a real use case for /..; and /.; segments. Hence
I think denying them should
be possible with a simple option without the need for a ProxyPass
directive or an additional
RewriteRule. This would also keep path parameters in other segments
as they are.
As said I am even happy if the default of this directive would keep
the current behavior.
> This sounds a bit like we want to reject "/.;" or "/..;" for the
> servlet case but still accept "/." and "/.." unconditionally for the
> non-servlet case. So possibly we want a general "AllowPathTraversal"
> directive (off by default) for the core to allow/reject "." and ".."
> AND proxy mapping=servlet to extend it to "/.;" or "/.;" (and
probably
> "/;" too since it's the same as "/.;" when MergeSlashes applies)?
I don't want to allow/deny '.' and '..'. Without path parameters I
just want to remove ('.') / shrink them ('..') without going
past root like we do today.
From the beginning of this dialog, that isn't the function of an HTTP/1
proxy. We have no business in that PER THE SPECS.
I don't understand why the Tomcat project and other servlet providers,
after given evidence they broke the spec, and downgrade of their
reservations of the ;params logic out of the URI spec, keep insisting
the behavior is necessary for the HTTP transport providers to consider.
I don't understand why, Ruediger, some keep defending the .; or ..; as a
normative acceptable path element, and refuse to consider the idea that
every such occurance is malicious, without evidence of a single legit
application of that formation.
If you don't want to let them slide, we *could* deny \.;.* and \.\.;.*
by default. Or we already *can* when ajp users would like to add rewrite
rules.
mod_proxy_http and mod_proxy_ajp behave the same way, mod_jk will return
DECLINED and end normally in 404.
; in the URI is for a parameter like ;foo=bar I was first just
suggesting to return 400 in possibly "unsafe" ..;/ URI using a parameter
to prevent "regressions", but I think we ended looking to something too
complex :-(
--
Cheers
Jean-Frederic
