Re: [PATCH v4 18/21] fuse: Add support for pid namespaces

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Wed, Jul 20, 2016 at 2:52 PM, Seth Forshee
<seth.forshee@xxxxxxxxxxxxx> wrote:

> It sounds like we need to remove the restriction on accessing the
> filesystem from a different pid namespace. I don't think this poses a
> security problem. However there's no pid mapping that is usable by the
> userspace fuse process, so what do we put in the fuse request? Probably
> the only candidates are 0 and 0xffffffff.
>
> So a question for the fuse developers - is one value or the other
> preferrable for fuse_in_header.pid when the pid cannot be mapped, and is
> this going to cause problems for any fuse filesystems? I suspect that
> few filesystems actually look at the pid anyway, and already for a
> filesystem mounted in a pid namespace the values being given to
> userspace won't be correct for the namespace of the fuse process.

pid = 0 sounds good.

The pid from the request is used for example to get the auxiliary
group list by libfuse (fuse_req_getgroups()).   That's not used by all
filesystems and it will return an error in case it can't find the proc
entry (which it won't for pid == 0).

It would be nice if we could transfer the group list through the
userspace/kernel protocol, since then it wouldn't depend on proc and
on being in the same pid namespace.  But that's another story.

Thanks,
Miklos
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]
  Powered by Linux