[jira] [Comment Edited] (HADOOP-12468) Partial group resolution failure should not result in user lockout

["Benoy Antony (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-12468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14972099#comment-14972099 ] 

Benoy Antony edited comment on HADOOP-12468 at 10/23/15 11:30 PM:
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We have faced this issue a few time on our cluster. The user was blocked and we have to fix the issue on a high priority. But in a healthy system , this issue should not occur.  

I have the following comments on this patch.

1. The implementation makes an assumption that the groupname  cannot be numeric. While a groupname consisting solely of digits is bad idea, systems allow groupnames consisting solely of digits. So the following check is not a good one. We need a better check to determine whether a group is unresolvable than isNumeric.

{code}
if (!groupName.isEmpty() && !StringUtils.isNumeric(groupName)) {
        groups.add(groupName);
 }
{code}

2.  Unnecessary modification. I believe the reason to have run "id -gn" is to keep primary group name as the first entry.

{code}
      : new String [] {"bash", "-c", "id -gn " + user + "&& id -Gn " + user};
      : new String [] {"bash", "-c", "id -Gn " + user};
{code}

3. Logging groupnames is not a good idea as the groupnames for some users could be a very long list.

4.String errMeessage = e.getMessage();
There is a typo in variable name. 
This variable is not used anywhere. But I believe the error message should be logged.


was (Author: benoyantony):
We have faced this issue a few time on our cluster. The user was blocked and we have to fix the issue on a high priority. But in a healthy system , this issue should not occur.  

I have the following comments on this patch.

1. The implementation makes an assumption that the groupname  cannot be numeric. While a groupname consisting solely of digits is bad idea, systems allows groupnames consisting solely of digits. So the following check is not a good one. We need a better check to determine whether a group is unresolvable than isNumeric.

{code}
if (!groupName.isEmpty() && !StringUtils.isNumeric(groupName)) {
        groups.add(groupName);
 }
{code}

2.  Unnecessary modification. I believe the reason to have run "id -gn" is to keep primary group name as the first entry.

{code}
      : new String [] {"bash", "-c", "id -gn " + user + "&& id -Gn " + user};
      : new String [] {"bash", "-c", "id -Gn " + user};
{code}

3. Logging groupnames is not a good idea as the groupnames for some users could be a very long list.

4.String errMeessage = e.getMessage();
There is a typo in variable name. 
This variable is not used anywhere. But I believe the error message should be logged.

> Partial group resolution failure should not result in user lockout
> ------------------------------------------------------------------
>
>                 Key: HADOOP-12468
>                 URL: https://issues.apache.org/jira/browse/HADOOP-12468
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: security
>    Affects Versions: 2.6.1
>         Environment: Linux
>            Reporter: Wei-Chiu Chuang
>            Assignee: Wei-Chiu Chuang
>            Priority: Minor
>         Attachments: HADOOP-12468.001.patch, HADOOP-12468.002.patch, HADOOP-12468.003.patch
>
>
> If a Hadoop cluster is configured to use ShellBasedUnixGroupsMapping for user/group name mapping, occasionally some group names may become unresolvable (for example, using SSSD). 
> ShellBasedUnixGroupsMapping uses shell command "id -Gn" to retrieve the group name of a user; however, the existing logic assumes that if the exit code of the command is non-zero, the user has no group name at all. The shell command in Linux returns non-zero exit code if a group name is not resolvable. Unfortunately, it is possible that a user belongs to multiple groups, and any partial failure in group name resolution would denied the user's access.
> On the other hand, the JNI implementation (JniBasedUnixGroupsMapping) is more resilient. If any group name is unresolvable, it is simply ignored, and whatever are resolvable are returned.
> It is arguable that if the group name is not resolvable, the administrator should configure their directory/authentication service correctly, and Hadoop is in no position to handle it, but since the existing unit tests assume the output of JNI-based and shell-based implementation are the same, we should improve the shell-based group name resolution, and make it as resilient as the JNI-based one.



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