On Mon, Apr 24, 2017 at 8:02 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote: > On Mon, Apr 24, 2017 at 7:25 AM, Djalal Harouni <tixxdz@xxxxxxxxx> wrote: >> On Sat, Apr 22, 2017 at 9:29 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote: >>> On Fri, Apr 21, 2017 at 11:51 PM, Andy Lutomirski <luto@xxxxxxxxxx> wrote: >>>> On Fri, Apr 21, 2017 at 5:12 PM, Djalal Harouni <tixxdz@xxxxxxxxx> wrote: >>>>> On Sat, Apr 22, 2017 at 1:51 AM, Andy Lutomirski <luto@xxxxxxxxxx> wrote: >>>>> >> [...] >>>>> * DCCP use after free CVE-2017-6074 >>>>> * n_hldc CVE-2017-2636 >>>>> * XFRM framework CVE-2017-7184 >>>>> * L2TPv3 CVE-2016-10200 >>>>> >>>>> Most of these need CAP_NET_ADMIN to be autoloaded, however we also >>>>> need CAP_NET_ADMIN for other things... therefore it is better to have >>>>> an extra facility that could coexist with CAP_NET_ADMIN and other >>>>> sandbox features. >>>>> >>>> >>>> I agree that the feature is important, but I think your implementation >>>> is needlessly dangerous. I imagine that the main uses that you care >>>> about involve containers. How about doing it in a safer way that >>>> works for containers? I can think of a few. For example: >>>> >>>> 1. A sysctl that, if set, prevents autoloading outside the root >>>> userns. This isn't very flexible at all, but it might work. >>>> >>>> 2. Your patch, but require privilege within the calling namespace to >>>> set the prctl. >>> >>> How about CAP_SYS_ADMIN || no_new_privs? >>> >>> -Kees >>> >> >> Yes I can update as per Andy suggestion to require privileges inside >> the calling namespace to set prctl. Other options that are not prctl >> based have more variants, that make them hard to use. >> >> So I would got with CAP_SYS_ADMIN in the calling userns || >> no_new_privs , I would have said CAP_SYS_MODULE in the userns but it >> seems better to standardize on CAP_SYS_ADMIN to set the prctl. > > Andy's concern is that it would provide an escalation from SYS_MODULE > to SYS_ADMIN through some privileged process being tricked through a > missing API provided by modules, so we have to use either SYS_ADMIN || > nnp. Yes, I would say that programs expect that maybe such functionality is not provided, but we don't know. I will update. Thanks! -- tixxdz -- 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
