MAPREDUCE-3737. The Web Application Proxy's is not documented very well. (Robert Evans via mahadev) - Merging r1236371 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1236373 13f79535-47bb-0310-9956-ffa450edef68

hadoop-mapreduce-project/CHANGES.txt

@@ -132,6 +132,9 @@ Release 0.23.1 - Unreleased
 
     MAPREDUCE-2765. DistCp Rewrite. (Mithun Radhakrishnan via mahadev)
 
+    MAPREDUCE-3737. The Web Application Proxy's is not documented very well.
+    (Robert Evans via mahadev)
+
   OPTIMIZATIONS
 
     MAPREDUCE-3567. Extraneous JobConf objects in AM heap. (Vinod Kumar

hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/WebApplicationProxy.apt.vm

@@ -0,0 +1,49 @@
+~~ Licensed under the Apache License, Version 2.0 (the "License");
+~~ you may not use this file except in compliance with the License.
+~~ You may obtain a copy of the License at
+~~
+~~   http://www.apache.org/licenses/LICENSE-2.0
+~~
+~~ Unless required by applicable law or agreed to in writing, software
+~~ distributed under the License is distributed on an "AS IS" BASIS,
+~~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+~~ See the License for the specific language governing permissions and
+~~ limitations under the License. See accompanying LICENSE file.
+
+  ---
+  YARN
+  ---
+  ---
+  ${maven.build.timestamp}
+
+Web Application Proxy
+
+  The Web Application Proxy is part of YARN.  By default it will run as part of
+  the Resource Manager(RM), but can be configured to run in stand alone mode.
+  The reason for the proxy is to reduce the possibility of web based attacks
+  through YARN.
+
+  In YARN the Application Master(AM) has the responsibility to provide a web UI
+  and to send that link to the RM.  This opens up a number of potential
+  issues.  The RM runs as a trusted user, and people visiting that web
+  address will treat it, and links it provides to them as trusted, when in
+  reality the AM is running as a non-trusted user, and the links it gives to
+  the RM could point to anything malicious or otherwise.  The Web Application
+  Proxy mitigates this risk by warning users that do not own the given
+  application that they are connecting to an untrusted site.
+
+  In addition to this the proxy also tries to reduce the impact that a malicious
+  AM could have on a user.  It primarily does this by stripping out cookies from
+  the user, and replacing them with a single cookie providing the user name of
+  the logged in user.  This is because most web based authentication systems will
+  identify a user based off of a cookie.  By providing this cookie to an
+  untrusted application it opens up the potential for an exploit.  If the cookie
+  is designed properly that potential should be fairly minimal, but this is just
+  to reduce that potential attack vector.  The current proxy implementation does
+  nothing to prevent the AM from providing links to malicious external sites,
+  nor does it do anything to prevent malicious javascript code from running as
+  well.  In fact javascript can be used to get the cookies, so stripping the
+  cookies from the request has minimal benefit at this time.
+
+  In the future we hope to address the attack vectors described above and make
+  attaching to an AM's web UI safer.

hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/index.apt.vm

@@ -47,4 +47,6 @@ MapReduce NextGen aka YARN aka MRv2
 
   * {{{./CapacityScheduler.html}Capacity Scheduler}}
 
+  * {{{./WebApplicationProxy.html}Web Application Proxy}}
+
 

hadoop-project/src/site/site.xml

@@ -61,6 +61,7 @@
       <item name="YARN Architecture" href="hadoop-yarn/hadoop-yarn-site/YARN.html"/>
       <item name="Writing Yarn Applications" href="hadoop-yarn/hadoop-yarn-site/WritingYarnApplications.html"/>
       <item name="Capacity Scheduler" href="hadoop-yarn/hadoop-yarn-site/CapacityScheduler.html"/>
+      <item name="Web Application Proxy" href="hadoop-yarn/hadoop-yarn-site/WebApplicationProxy.html"/>
     </menu>
 
     <menu name="YARN REST API's" inherit="top">