"Michael Kerrisk (man-pages)" <mtk.manpages@xxxxxxxxx> writes: > Hi Eric, > > On 25 January 2017 at 14:58, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: >> "Michael Kerrisk (man-pages)" <mtk.manpages@xxxxxxxxx> writes: >> >>> I would like to write code that discovers the namespace setup on a live >>> system. The NS_GET_PARENT and NS_GET_USERNS ioctl() operations added in >>> Linux 4.9 provide much of what I want, but there are still a couple of >>> small pieces missing. Those pieces are added with this patch series. >> >> So it looks like the -EOVERFLOW change broke your example program. >> Causing it to abort if -EOVERFLOW is hit. Do we really want to return >> -EOVERFLOW? Or do you want to fix your program? > > Bother! Yes, I should have kept the example program in sync. (I > overlooked that it was not any more in sync.) > > So, I want to make sure I understand correctly, before I aswer your > question. Suppose we have > > 1. Outer namespace owned by UID 0 > 2. Inner namespace owned by UID 1000 > 3. A UID mapping in the inner namespace that maps '0 1000 1' > 4. A processs, X, in the outer namespace with UID 0 (and all caps). > > That's the case you're meaning, right? I think so I just noticed you did not handle -EOVERFLOW in the one NS_GET_OWNER_UID call. > So, UID 0 doesn't have a > mapping into the inner namespace, but does have all capabilities in > that inner namespace, right? That is correct. Eric -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
