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https://issues.apache.org/jira/browse/SSHD-1042?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Work on SSHD-1042 started by Lyor Goldstein.
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> Command Limiting Policy SSH_FXP_READDIR closing connection
> ----------------------------------------------------------
>
> Key: SSHD-1042
> URL: https://issues.apache.org/jira/browse/SSHD-1042
> Project: MINA SSHD
> Issue Type: New Feature
> Reporter: Shahbaz
> Assignee: Lyor Goldstein
> Priority: Major
> Attachments: apache rmdir.PNG, maverick filesystem.PNG
>
>
> *This are the below commands which prevent the execution of process for the
> user at instance level relating to permission of open, read, write, opendir,
> readdir, remove, rename, makedir, removedir respectively.*
> *SSH_FXP_OPEN*
> *SSH_FXP_READ*
> *SSH_FXP_WRITE*
> *SSH_FXP_OPENDIR*
> *SSH_FXP_READDIR*
> *SSH_FXP_REMOVE*
> *SSH_FXP_RENAME*
> *SSH_FXP_MKDIR*
> *SSH_FXP_RMDIR*
> *But the command for* *SSH_FXP_READDIR is not executed as it directly closes
> the connection. This connection is closed because while throwing the
> exception it directly calls destroy method from filesystem. Is there any
> workaround to inhibit its execution when we extend sftpsubsytem class where
> exception is thrown.***
> *While reading the directory when SH_FXP_READDIR is applied, the operation is
> interrupted, as it evokes the destroy function to close the connection
> directly when an IOException is thrown. The issue is how can we make sure the
> destroy function is not called, when exception is thrown in a class which
> extends SFTPSubsystem.*
>
> *Exact working scenarios of the above issue:*
> We have our implementation of Command Limiting Policy to prevent specific IP
> addresses or users from executing
> certain commands on an SFTP server.
> After validation of the policy, we don't want user to perform the operation
> based on the command which is applied on the policy.
> For example: When the SSH_FXP_OPENDIR is invoked, the user is restricted
> from open directory operation.
> Our issue is related to command SSH_FXP_READDIR command.
> Expected Behaviour : Prevent user from reading the directory when sftp ls
> command is executed, by giving the message like "Unable to read the
> directory".
> But we see that, though we throw AcessDeniedException on validating the
> policy, the connection is getting closed, and we get an error as "Connection
> closed".
> We have the same implementation for validating the policy and we throw
> AcessDeniedException in case of all the sftp commands(if we need to prevent
> the user/ip)
> We find that all the sftp commands work as expected, except SSH_FXP_READDIR.
> The difference we find is that destroy() method in SFTP Subsystem is getting
> invoked after our policy validation in SSH_FXP_READDIR. In case of all other
> commands, we dont see destro() getting invoked.
>
> Is there any specific thing that needs to be handled in our implementation to
> prevent destroy() from getting invoked and connection getting closed. We are
> unable to find why destroy() is invoked in case of SSH_FXP_READDIR command,
> even though AcessDeniedException is thrown from our implementation.
>
>
>
> *Below attached are the images which shows how destroy is invoked in both
> maverick and apache case.*
>
>
>
>
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