[lkml]   [2018]   [Mar]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Invalid /proc/<pid>/fd/{0,1,2} symlinks with TIOCGPTPEER
On Wed, Mar 07, 2018 at 11:44:35AM -0800, Linus Torvalds wrote:
> On Wed, Mar 7, 2018 at 8:17 AM, Christian Brauner
> <> wrote:
> >
> > unshare --mount
> > mount --bind /dev/pts/ptmx /dev/ptmx
> > chmod 666 /dev/ptmx
> Oh. Why are you using a bind mount in the first place?

Containers employing user namespaces can't mknod() and because of the
way some LSMs check access permissions (path-based AppArmor being one
example) a symlink to /dev/pts/ptmx won't work either so a bind-mount
seems like the most reliable solution.

> Anyway, I guess we just have to add another special case for this.
> Which doesn't look horrible. Right now path_pts() just does
> ret = path_parent_directory(path);
> and that simply doesn't work for a bind mount file.
> I think we could just change path_parent_directory() to go through
> file bind mounts. The other user is follow_dotdot(), but that always
> takes a directory, so it wouldn't be affected.
> But it's probably safer to just teach path_pts to just walk up the
> bind mount first, and then do the existing path_parent_directory.
> Anybody want to just try that thing?

Sure. I can try and take a look.


 \ /
  Last update: 2018-03-08 09:20    [W:0.049 / U:3.000 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site