Messages in this thread | | | Date | Fri, 5 Oct 2012 16:00:09 -0400 | From | "J. Bruce Fields" <> | Subject | Re: [RFC PATCH 0/5] net: socket bind to file descriptor introduced |
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On Tue, Sep 04, 2012 at 03:00:07PM -0400, bfields wrote: > On Mon, Aug 20, 2012 at 02:18:13PM +0400, Stanislav Kinsbursky wrote: > > 16.08.2012 07:03, Eric W. Biederman пишет: > > >Stanislav Kinsbursky <skinsbursky@parallels.com> writes: > > > > > >>This patch set introduces new socket operation and new system call: > > >>sys_fbind(), which allows to bind socket to opened file. > > >>File to bind to can be created by sys_mknod(S_IFSOCK) and opened by > > >>open(O_PATH). > > >> > > >>This system call is especially required for UNIX sockets, which has name > > >>lenght limitation. > > >> > > >>The following series implements... > > > > > >Hmm. I just realized this patchset is even sillier than I thought. > > > > > >Stanislav is the problem you are ultimately trying to solve nfs clients > > >in a container connecting to the wrong user space rpciod? > > > > > > > Hi, Eric. > > The problem you mentioned was the reason why I started to think about this. > > But currently I believe, that limitations in unix sockets connect or > > bind should be removed, because it will be useful it least for CRIU > > project. > > > > >Aka net/sunrpc/xprtsock.c:xs_setup_local only taking an absolute path > > >and then creating a delayed work item to actually open the unix domain > > >socket? > > > > > >The straight correct and straight forward thing to do appears to be: > > >- Capture the root from current->fs in xs_setup_local. > > >- In xs_local_finish_connect change current->fs.root to the captured > > > version of root before kernel_connect, and restore current->fs.root > > > after kernel_connect. > > > > > >It might not be a bad idea to implement open on unix domain sockets in > > >a filesystem as create(AF_LOCAL)+connect() which would allow you to > > >replace __sock_create + kernel_connect with a simple file_open_root. > > > > > > > I like the idea of introducing new family (AF_LOCAL_AT for example) > > and new sockaddr for connecting or binding from specified root. The > > only thing I'm worrying is passing file descriptor to unix bind or > > connect routine. Because this approach doesn't provide easy way to > > use such family and sockaddr in kernel (like in NFS example). > > > > >But I think the simple scheme of: > > >struct path old_root; > > >old_root = current->fs.root; > > >kernel_connect(...); > > >current->fs.root = old_root; > > > > > >Is more than sufficient and will remove the need for anything > > >except a purely local change to get nfs clients to connect from > > >containers. > > > > > > > That was my first idea. > > So is this what you're planning on doing now?
What ever happened to this?
--b.
> > > And probably it would be worth to change all > > fs_struct to support sockets with relative path. > > What do you think about it? > > I didn't understand the question. Are you suggesting that changes to > fs_struct would be required to make this work? I don't see why. > > --b. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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