Re: hardening mod_write and mod_proxy like mod_jk with servletnormalize
On Mon, Jul 20, 2020, 10:24 Ruediger Pluem wrote:
>
>
> On 7/20/20 4:45 PM, Yann Ylavic wrote:
> > On Thu, Jul 16, 2020 at 10:31 PM Eric Covener wrote:
> >>
> >> On Thu, Jul 16, 2020 at 3:31 PM Ruediger Pluem
> 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.
Re: hardening mod_write and mod_proxy like mod_jk with servletnormalize
On 7/20/20 4:45 PM, Yann Ylavic wrote:
> On Thu, Jul 16, 2020 at 10:31 PM Eric Covener wrote:
>>
>> On Thu, Jul 16, 2020 at 3:31 PM Ruediger Pluem 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.
Regards
Rüdiger
Re: hardening mod_write and mod_proxy like mod_jk with servletnormalize
On Thu, Jul 16, 2020 at 10:31 PM Eric Covener wrote: > > On Thu, Jul 16, 2020 at 3:31 PM Ruediger Pluem 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. 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. 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)? Regards; Yann.
Re: svn commit: r1879641 - in /httpd/httpd/branches/2.4.x: ./ CHANGES STATUS server/util_script.c
On 7/18/20 10:11 AM, Luca Toscano wrote: > Hi Ruediger, > > On Wed, Jul 15, 2020 at 10:04 AM Ruediger Pluem wrote: >> >> >> On 7/15/20 9:06 AM, Luca Toscano wrote: >>> Hi everybody, >>> >>> getting back on this. I checked mergeinfo and r1879253 r1879348 are >>> not listed, what is the best path forward to fix this? (Asking because >>> I have never merged from trunk, and I am not sure what is the best >>> path forward). >> >> Try >> >> svn merge --record-only -c 1879253,1879348 >> https://svn.apache.org/repos/asf/httpd/httpd/trunk . >> >> in a freshly svn up'ed working copy of 2.4.x. > > Thanks for the answer. IIUC the above command takes care of updating > mergeinfo with the missing revs, but the problem is (I think) that > they didn't get merged in the first place along with the others (so > they are missing from 2.4.x). Since I never merged commits into 2.4.x, > I was wondering what to do to avoid messing up the state :) Good catch. The backport was incomplete as only the first of the list of revisions was backported. Fixed in r1880060. Regards Rüdiger
