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Re: [Qemu-devel] [PATCH] block: Add support for Secure Shell (ssh) block
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH] block: Add support for Secure Shell (ssh) block device. |
Date: |
Thu, 21 Mar 2013 16:26:23 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Thu, Mar 21, 2013 at 01:38:58PM +0000, Richard W.M. Jones wrote:
> From: "Richard W.M. Jones" <address@hidden>
>
> qemu-system-x86_64 -drive file=ssh://hostname/some/image
>
> QEMU will ssh into 'hostname' and open '/some/image' which is made
> available as a standard block device.
>
> You can specify a username (ssh://address@hidden/...) and/or a port number
> (ssh://host:port/...).
I can see this being handy for qemu-img since it gives you the ability
to work with remote image files.
> Current limitations:
>
> - Authentication must be done without passwords or passphrases, using
> ssh-agent. Other authentication methods are not supported. (*)
>
> - Does not check host key. (*)
>
> - New remote files cannot be created. (*)
Would be important to fix these limitations. Authentication methods to
make this more usable. Host key check for security. File creation for
qemu-img.
> - Uses coroutine read/write, instead of true AIO. (libssh2 supports
> non-blocking access, so this could be fixed with some effort).
This patch does not really use coroutines - the SSH I/O is blocking!
Coroutines must submit the SSH I/O and then yield so the QEMU event loop
can get on with other work. When SSH I/O finishes the request's
coroutine is re-entered and the request gets completed.
> - Blocks during connection and authentication.
Right now the code also blocks while SSH I/O takes place.
> (*) = potentially easy fix
>
> This is implemented using libssh2 on the client side. The server just
> requires a regular ssh daemon with sftp-server support. Most ssh
> daemons on Unix/Linux systems will work out of the box.
How much of a win over sshfs is this?
sshfs can be mounted by unprivileged users and QEMU accesses it like a
regular file. So the sshfs approach already works today.
Stefan
- [Qemu-devel] [PATCH] Add support for Secure Shell (ssh) block device., Richard W.M. Jones, 2013/03/21
- [Qemu-devel] [PATCH] block: Add support for Secure Shell (ssh) block device., Richard W.M. Jones, 2013/03/21
- Re: [Qemu-devel] [PATCH] block: Add support for Secure Shell (ssh) block device.,
Stefan Hajnoczi <=
- Re: [Qemu-devel] [PATCH] block: Add support for Secure Shell (ssh) block device., Stefan Hajnoczi, 2013/03/21
- Re: [Qemu-devel] [PATCH] block: Add support for Secure Shell (ssh) block device., Richard W.M. Jones, 2013/03/21
- [Qemu-devel] [PATCH] block/curl: Add support for Secure Shell (ssh/sftp) block device, Richard W.M. Jones, 2013/03/22
- Re: [Qemu-devel] [PATCH] block/curl: Add support for Secure Shell (ssh/sftp) block device, Stefan Hajnoczi, 2013/03/22
- Re: [Qemu-devel] [PATCH] block/curl: Add support for Secure Shell (ssh/sftp) block device, Richard W.M. Jones, 2013/03/25
- Re: [Qemu-devel] [PATCH] block/curl: Add support for Secure Shell (ssh/sftp) block device, Stefan Hajnoczi, 2013/03/25
Re: [Qemu-devel] [PATCH] block: Add support for Secure Shell (ssh) block device., Kevin Wolf, 2013/03/25