Quoting Eric W. Biederman (ebiederm@xxxxxxxxxxxx): > "Serge E. Hallyn" <serge@xxxxxxxxxx> writes: > > > Quoting Eric W. Beiderman (ebiederm@xxxxxxxxxxxx): > >> From: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> > >> > > > > Oh, perhaps this is the right place in the thread to discuss the issue of > > what to do with file capabilities? I'm ok waiting until the next iteration > > to even discuss it, so long as we start by refusing setting of fcaps by > > any task not in init_user_ns. > > For now we do refuse all callers in the init_user_ns because that path > is protected by a capable and not an ns_capable call. > > And as a general policy I have pushed all of the changes from capable to > ns_capable out till after we get these other user namespace bits so we > can get the patches reviewed so hopefully don't enable something that is > not safe. > > Let's just note here that when we ever get a filesystem mounted in > something other than the init_user_ns or otherwise allow file > capabilities that do not belong to the init_user_ns we need to an > additional exec check to avoid a security issue for processes in the > init_user_ns using those credentials. > > The other direction the init_user_ns setting file caps on a file and use > using them in a child namespace seems safe, and practical because of the > way we handle capabilities. Aka if you have a capability in an outer > user namespace you also have it in a child user namespace. Which means > a file cap exec today will give you just the capabilities in the child > user namespace. > > Something else to think about when we reach filesystems mounted in > different user namespaces (aka unprivileged mounts) are security > labels on files in different user namespaces. Not any kind of immediate > concern but something we may have to handle eventually. An interesting concern to discuss at the security mini-summit (or just at the UDS session). -serge -- 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
