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https://issues.apache.org/jira/browse/HDFS-13965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17247381#comment-17247381
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István Fajth commented on HDFS-13965:
-------------------------------------
Ok, so to refine my understanding:
There is an application running as root, which operates with the following flow:
Software starts -> at one point changes the uid runs kinit with a specified
ticket cache in the default path -> later on connections to HDFS uses that
ticket cache based on KRB5CCNAME environment variable
During HDFS accesses the software is already running as root.
Auto renewal happens in the context of these HDFS accesses at one point in time
later on, when the software is running as root, therefore the ticket cache file
ownership is changed by kerberos libraries as expected, as the ticket should
belong to the authenticating user.
What I still don't get: why do you need to kinit as the halsys user if
otherwise the software is using the ticket cache as root, and as with the
keytab any user can authenticate and get a ticket as the halsys user?
What I would do:
- run a kinit at software startup as root specifying
/etc/mysoftware/ticketcahce as the ticketcache
- in the software's environment I would set KRB5CCNAME to point to
/etc/mysoftware/ticketcahce
With that we let alone the whole system and any other thing in the system, we
kinit to have a ticket for the software, as we can not use a keytab based auth
in the C lib as it seems, and then from the environment we ensure that the
software uses that ticket in the cache exclusive for this application. And in
this case as the application is running as root, we can ignore the question of
who owns the ticket cache, as root will own it, the software running as root
will be able to access it, and noone and nothing else in the system will care
about this particular ticket cache, for which the path can be anything not just
/etc/mysoftware/ticketcahce, it can not be one thing, the default ticket cache
path of any user...
> hadoop.security.kerberos.ticket.cache.path setting is not honored when KMS
> encryption is enabled.
> -------------------------------------------------------------------------------------------------
>
> Key: HDFS-13965
> URL: https://issues.apache.org/jira/browse/HDFS-13965
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs-client, kms
> Affects Versions: 2.7.3, 2.7.7
> Reporter: LOKESKUMAR VIJAYAKUMAR
> Assignee: Kitti Nanasi
> Priority: Major
>
> _We use the *+hadoop.security.kerberos.ticket.cache.path+* setting to provide
> a custom kerberos cache path for all hadoop operations to be run as specified
> user. But this setting is not honored when KMS encryption is enabled._
> _The below program to read a file works when KMS encryption is not enabled,
> but it fails when the KMS encryption is enabled._
> _Looks like *hadoop.security.kerberos.ticket.cache.path* setting is not
> honored by *createConnection on KMSClientProvider.java.*_
>
> HadoopTest.java (CLASSPATH needs to be set to compile and run)
>
> import java.io.InputStream;
> import java.net.URI;
> import org.apache.hadoop.conf.Configuration;
> import org.apache.hadoop.fs.FileSystem;
> import org.apache.hadoop.fs.Path;
>
> public class HadoopTest {
> public static int runRead(String[] args) throws Exception{
> if (args.length < 3) {
> System.err.println("HadoopTest hadoop_file_path
> hadoop_user kerberos_cache");
> return 1;
> }
> Path inputPath = new Path(args[0]);
> Configuration conf = new Configuration();
> URI defaultURI = FileSystem.getDefaultUri(conf);
>
> conf.set("hadoop.security.kerberos.ticket.cache.path",args[2]);
> FileSystem fs =
> FileSystem.newInstance(defaultURI,conf,args[1]);
> InputStream is = fs.open(inputPath);
> byte[] buffer = new byte[4096];
> int nr = is.read(buffer);
> while (nr != -1)
> {
> System.out.write(buffer, 0, nr);
> nr = is.read(buffer);
> }
> return 0;
> }
> public static void main( String[] args ) throws Exception {
> int returnCode = HadoopTest.runRead(args);
> System.exit(returnCode);
> }
> }
>
>
>
> [root@lstrost3 testhadoop]# pwd
> /testhadoop
>
> [root@lstrost3 testhadoop]# ls
> HadoopTest.java
>
> [root@lstrost3 testhadoop]# export CLASSPATH=`hadoop classpath --glob`:.
>
> [root@lstrost3 testhadoop]# javac HadoopTest.java
>
> [root@lstrost3 testhadoop]# java HadoopTest
> HadoopTest hadoop_file_path hadoop_user kerberos_cache
>
> [root@lstrost3 testhadoop]# java HadoopTest /loki/loki.file loki
> /tmp/krb5cc_1006
> 18/09/27 23:23:20 WARN util.NativeCodeLoader: Unable to load native-hadoop
> library for your platform... using builtin-java classes where applicable
> 18/09/27 23:23:21 WARN shortcircuit.DomainSocketFactory: The short-circuit
> local reads feature cannot be used because libhadoop cannot be loaded.
> Exception in thread "main" java.io.IOException:
> org.apache.hadoop.security.authentication.client.AuthenticationException:
> GSSException: *{color:#FF0000}No valid credentials provided (Mechanism level:
> Failed to find any Kerberos tgt){color}*
> at
> {color:#FF0000}*org.apache.hadoop.crypto.key.kms.KMSClientProvider.createConnection(KMSClientProvider.java:551)*{color}
> at
> org.apache.hadoop.crypto.key.kms.KMSClientProvider.decryptEncryptedKey(KMSClientProvider.java:831)
> at
> org.apache.hadoop.crypto.key.KeyProviderCryptoExtension.decryptEncryptedKey(KeyProviderCryptoExtension.java:388)
> at
> org.apache.hadoop.hdfs.DFSClient.decryptEncryptedDataEncryptionKey(DFSClient.java:1393)
> at
> org.apache.hadoop.hdfs.DFSClient.createWrappedInputStream(DFSClient.java:1463)
> at
> org.apache.hadoop.hdfs.DistributedFileSystem$4.doCall(DistributedFileSystem.java:333)
> at
> org.apache.hadoop.hdfs.DistributedFileSystem$4.doCall(DistributedFileSystem.java:327)
> at
> org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
> at
> org.apache.hadoop.hdfs.DistributedFileSystem.open(DistributedFileSystem.java:340)
> at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:786)
> at HadoopTest.runRead(HadoopTest.java:18)
> at HadoopTest.main(HadoopTest.java:29)
> Caused by:
> org.apache.hadoop.security.authentication.client.AuthenticationException:
> GSSException: No valid credentials provided (Mechanism level: Failed to find
> any Kerberos tgt)
> at
> org.apache.hadoop.security.authentication.client.KerberosAuthenticator.doSpnegoSequence(KerberosAuthenticator.java:333)
> at
> org.apache.hadoop.security.authentication.client.KerberosAuthenticator.authenticate(KerberosAuthenticator.java:203)
> at
> org.apache.hadoop.security.token.delegation.web.DelegationTokenAuthenticator.authenticate(DelegationTokenAuthenticator.java:133)
> at
> org.apache.hadoop.security.authentication.client.AuthenticatedURL.openConnection(AuthenticatedURL.java:216)
> at
> org.apache.hadoop.security.token.delegation.web.DelegationTokenAuthenticatedURL.openConnection(DelegationTokenAuthenticatedURL.java:322)
> at
> org.apache.hadoop.crypto.key.kms.KMSClientProvider$1.run(KMSClientProvider.java:542)
> at
> org.apache.hadoop.crypto.key.kms.KMSClientProvider$1.run(KMSClientProvider.java:537)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:422)
> at
> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1869)
> at
> org.apache.hadoop.crypto.key.kms.KMSClientProvider.createConnection(KMSClientProvider.java:536)
> ... 11 more
> Caused by: GSSException: No valid credentials provided (Mechanism level:
> Failed to find any Kerberos tgt)
> at
> sun.security.jgss.krb5.Krb5InitCredential.getInstance(Krb5InitCredential.java:147)
> at
> sun.security.jgss.krb5.Krb5MechFactory.getCredentialElement(Krb5MechFactory.java:122)
> at
> sun.security.jgss.krb5.Krb5MechFactory.getMechanismContext(Krb5MechFactory.java:187)
> at
> sun.security.jgss.GSSManagerImpl.getMechanismContext(GSSManagerImpl.java:224)
> at
> sun.security.jgss.GSSContextImpl.initSecContext(GSSContextImpl.java:212)
> at
> sun.security.jgss.GSSContextImpl.initSecContext(GSSContextImpl.java:179)
> at
> org.apache.hadoop.security.authentication.client.KerberosAuthenticator$1.run(KerberosAuthenticator.java:309)
> at
> org.apache.hadoop.security.authentication.client.KerberosAuthenticator$1.run(KerberosAuthenticator.java:285)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:422)
> at
> org.apache.hadoop.security.authentication.client.KerberosAuthenticator.doSpnegoSequence(KerberosAuthenticator.java:285)
> ... 21 more
>
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