On 8/8/12 9:38 AM, Martin Gainty wrote:
> http://download.oracle.com/otn-pub/jcp/jacc-1.0-fr-spec-oth-JSpec/jacc-1_0-fr-spec.pdf?AuthParam=1344431271_c27abd82b7b45ea09fbf22ba55ab8381
>
> • If the pattern is a*path prefix pattern*, it must be qualified by
> every path-prefix pattern in the deployment descriptor matched by (the
> pattern being qualified) *and*
> different from the pattern being qualified.
> The pattern must also be qualified/by every exact pattern /appearing
> in the deployment descriptor that is matched by the pattern being
> qualified.
>
> • If the pattern is an*extension pattern*, it must be qualified by
> every path-prefix pattern appearing in the deployment descriptor *and*
> every exact pattern in the deployment descriptor that is matched by
> the pattern being qualified.
>
> • If the pattern is the*default pattern*, "/", it must be qualified by
> every other pattern /except the default pattern appearing in the
> deployment descriptor./
>
> • If the pattern is an *exact pattern*, its qualified form must not
> contain any qualifying
> patterns.
> icantly
> it seems the spec lacks specific examples for each pattern use case
> the statistical probability of mis-interpretation for each pattern and
> mis-implementation is increased
Martin,
In a JACC compatible Servlet container such as Glassfish, when the
servlet path as derived from the request equals "/"
an empty-string servlet path is used in its stead in security-constraint
matching to ensure that the url-pattern "/"
is never an exact match for any request.
IOW, this was done to ensure that in this corner case, as in all other
cases, the default pattern "\' will have the lowest priority.
In the JACC spec this is spelled out in several places, most notable of
which may be:
4.1.1 Permission Names for Transport and Pre-Dispatch Decisions
The name of the permission checked in a transport or pre-dispatch
decision must
be the unqualified request URI minus the context path. All colon characters
occurring within the name must be represented using escaped encoding1.
For the
special case where this transformation of the request URI yields the
URLPattern
"/", the empty string URLPattern, "", must be used as the permission name.
For the special case where the empty string must be substituted for the "/"
pattern in the permission evaluation, all target related processing
(including
servlet mapping, filter mapping, and form based login processing) must be
performed using the original pattern, "/".
fwiw, there is similar language in the Servlet spec, although its
purpose may never have been revealed, and I personally
find it a bit difficult to understand.
As defined in the Servlet Spec Section 3.5 Request Path Elements
Servlet Path: The path section that directly corresponds to the
mapping which
activated this request. This path starts with a ’/’ character except
in the case
where the request is matched with the ‘/*’ or ““ pattern, in which
case it is an
empty string.
and of a similar nature 12.2 ...
"The empty string ("") is a special URL pattern that exactly maps to the
application's context root, i.e., requests of the form
http://host:port/<context-
root>/. In this case the path info is ’/’ and the servlet path and
context path is
empty string (““)."
To your point about examples, I agree that it would be helpful if this
aspect of security-constraint
matching was made more visible in developer documentation.
For example, if you want to define a security constraint on the root of
your application, you would use the empty-string pattern to do so.
Ron
> Martin Gainty
> ______________________________________________
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> ------------------------------------------------------------------------
> Subject: Re:
> From: v.b.kumar.jayanti_at_oracle.com
> Date: Wed, 8 Aug 2012 11:49:49 +0530
> CC: ron.monzillo_at_oracle.com; jeff.tancill_at_oracle.com;
> paul.hendley_at_oracle.com
> To: users_at_glassfish.java.net
>
>
> On Aug 8, 2012, at 11:21 AM, KumarJayanti wrote:
>
> *
> *
>
> On Aug 7, 2012, at 7:41 PM, CASALINO, Matteo Maria wrote:
>
> Hello Everyone,
>
> I believe I found a problem in the Glassfish interpretation of
> some combinations of security constraints in the deployment
> descriptor of web applications.
>
> In particular, the problem seems to occur whenever one or more
> security constraints apply to the context root of a web
> application (/) and other constraints apply instead to every
> path under the context root (/*). One such example is given by
> the following configuration:
>
> <!-- Security Constraint SC1 -->
> <security-constraint>
> <web-resource-collection>
> <web-resource-name/>
> <url-pattern>/*</url-pattern>
> </web-resource-collection>
> </security-constraint>
>
> <!-- Security Constraint SC2 -->
> <security-constraint>
> <web-resource-collection>
> <web-resource-name/>
> <url-pattern>/</url-pattern>
> </web-resource-collection>
> <auth-constraint/>
> </security-constraint>
>
> According to Servlet spefication [1, 13.8.3] a HTTP request
> directed to the context root (such as "GET /") shall be denied
> in this case, since SC2 has the "best matching" URL pattern.
> In contrast, Glassfish allows any (even unauthenticated)
> requests to the context root. Notice that Tomcat behaves
> instead as prescribed by the Servlet specification and denies
> all the requests directed to the context root.
>
> Does anyone know if there is any explanation to this behaviour?
>
>
> It seems like an interesting corner case that i never experimented
> before, but here are some relevant points from the JSR 115 Spec
> and Servlet Spec.
>
> *-------------------------------------------------------*
> *Servlet URL-Pattern Matching Rules (JSR 115)*
> *-----------------------------------------------*
> *
> *
> this pattern is the special default pattern,"/",which matches all
> other patterns.
>
> Qualified URL Pattern Names (JSR 115)
> ------------------------------------
> If the pattern is the default pattern,"/",it must be qualified by
> every other pattern except the default pattern appearing in the
> deployment descriptor.
>
> Any pattern, qualified by a pattern that matches it, is overridden
> and made irrelevant (in the translation) by the qualifying
> pattern. Specifically, all extension patterns and the default
> pattern are made irrelevant by the presence of the path prefix
> pattern "/*" in a deployment descriptor.
>
> Combining Constraints (servlet spec)
> ----------------------------------
> The special case of an authorization constraint that names no
> roles shall combine with any other constraints to override their
> affects and cause access to be precluded.
> ---------------------------------------------
>
> Please note the statement above about the presence of path prefix
> pattern "/*" making the default pattern "/" irrelevant. So the
> granted.policy generated in this case for glassfish is :
>
> grant {
> permission javax.security.jacc.WebUserDataPermission "/*";
> permission javax.security.jacc.WebResourcePermission "/*";
> };
>
> And it allows access.
>
> On the other hand in SC1 if you remove the path prefix pattern
> and change it to something else say "/xyz" then you can see the
> deny behavior due to SC2 kicking in :
>
> Here is the granted.policy
>
> grant {
> permission javax.security.jacc.WebUserDataPermission "/xyz";
> permission javax.security.jacc.WebResourcePermission "/xyz";
> };
>
> and exclude.policy generated in this case :
>
> grant {
> permission javax.security.jacc.WebUserDataPermission "/:/xyz";
> permission javax.security.jacc.WebResourcePermission "/:/xyz";
> };
>
> As you can see the final result is to deny access to /xyz
>
>
> Correction : i meant deny access to "/" here.
>
> . So i am tending to believe that GlassFish is correct in your
> case. I am CCing Ron who is the author of these specs for his
> comments.
>
> regards,
> kumar
>
>
>
>
> [1]
> http://jcp.org/aboutJava/communityprocess/final/jsr315/index.html
>
>
> Matteo Casalino
> Research Associate
> Security & Trust
> SAP Research, SAP Labs France SAS
> 805, avenue du Dr. Maurice Donat
> 06254 Mougins Cedex
> T +334 92 28 - 63 42
> E matteo.maria.casalino_at_sap.com
> <mailto:matteo.maria.casalino_at_sap.com>
> W http://www.sap.com/research
>
>
>