Messages in this thread | | | Date | Wed, 25 May 2011 16:38:06 -0500 | From | "Serge E. Hallyn" <> | Subject | Re: [GIT PULL] Namespace file descriptors for 2.6.40 |
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Quoting C Anthony Risinger (anthony@xtfx.me): > On Mon, May 23, 2011 at 4:05 PM, Eric W. Biederman > <ebiederm@xmission.com> wrote: > > > > This tree adds the files /proc/<pid>/ns/net, /proc/<pid>/ns/ipc, > > /proc/<pid>/ns/uts that can be opened to refer to the namespaces of a > > process at the time those files are opened, and can be bind mounted to > > keep the specified namespace alive without a process. > > > > This tree adds the setns system call that can be used to change the > > specified namespace of a process to the namespace specified by a system > > call. > > i just have a quick question regarding these, apologies if wrong place > to respond -- i trimmed to lists only. > > if i understand correctly, mount namespaces (for example), allow one > to build such constructs as "private /tmp" and similar that even > `root` cannot access ... and there are many reasons `root` does not > deserve to completely know/interact with user processes (FUSE makes a > good example ... just because i [user] have SSH access to a machine, > why should `root`?) > > would these /proc additions break such guarantees? IOW, would it now > become possible for `root` to inject stuff into my private namespaces, > and/or has these guarantees never existed and i am mistaken? is there > any kind of ACL mechanism that endows the origin process (or similar) > with the ability to dictate who can hold and/or interact with these > references?
If for instance you have a file open in your private /tmp, then root in another mounts ns can open the file through /proc/$$/fd/N anyway. If it's a directory, he can now traverse the whole fs.
-serge
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