Messages in this thread | | | Date | Fri, 4 Dec 2015 14:43:19 -0600 | From | Seth Forshee <> | Subject | Re: [PATCH 18/19] fuse: Restrict allow_other to the superblock's namespace or a descendant |
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On Fri, Dec 04, 2015 at 02:05:41PM -0600, Serge E. Hallyn wrote: > Quoting Seth Forshee (seth.forshee@canonical.com): > > Unprivileged users are normally restricted from mounting with the > > allow_other option by system policy, but this could be bypassed > > for a mount done with user namespace root permissions. In such > > cases allow_other should not allow users outside the userns > > to access the mount as doing so would give the unprivileged user > > the ability to manipulate processes it would otherwise be unable > > to manipulate. Restrict allow_other to apply to users in the same > > userns used at mount or a descendant of that namespace. > > > > Signed-off-by: Seth Forshee <seth.forshee@canonical.com> > > --- > > fs/fuse/dir.c | 10 ++++++++-- > > 1 file changed, 8 insertions(+), 2 deletions(-) > > > > diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c > > index f67f4dd86b36..5b8edb1203b8 100644 > > --- a/fs/fuse/dir.c > > +++ b/fs/fuse/dir.c > > @@ -1018,8 +1018,14 @@ int fuse_allow_current_process(struct fuse_conn *fc) > > { > > const struct cred *cred; > > > > - if (fc->flags & FUSE_ALLOW_OTHER) > > - return 1; > > + if (fc->flags & FUSE_ALLOW_OTHER) { > > + struct user_namespace *ns; > > + for (ns = current_user_ns(); ns; ns = ns->parent) { > > + if (ns == fc->user_ns) > > + return 1; > > + } > > use current_in_userns() ?
Yes, it should. I wrote this before I wrote the patch which adds that function and never thought to go back to change it here.
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