On Thu, Nov 12, 2020 at 2:38 AM Sergio Lopez <slp@xxxxxxxxxx> wrote: > > (This message was originally sent to the Packaging mailing list, where > Jason Tibbitts pointed that this is a restriction requested by the > Kernel team, and it'll be your opinion the one that will prevail here) > > Hi, > > The document "What can be packaged" from "Fedora Packaging > Guidelines", in the section "Only one kernel package" [1], states that > "Fedora allows only a single kernel package; packages containing > alternate kernels are not allowed in the distribution." > > While not explicitly stated there, I suspect (please correct me if I'm > wrong) that statement was written with the idea of preventing > alternate kernels that could be used to boot the system. With this > premise in mind, I was wondering if non-bootable kernels (that is, > kernels in a binary format that's not accepted by a conventional boot > loader) would be accepted for packaging. > > I'm asking this because I would like to package "libkrunfw" [2], a > dynamic library that bundles an slightly modified minimalist Linux > kernel. The library doesn't really link against the kernel (in the > sense that it doesn't resolve any symbols nor calls to any of its > code), it just bundles it in a binary format that allows it to be > directly injected in a KVM memory region, so it's quite similar to a > compressed image format, but for a different use case. > > "libkrunfw" is consumed by "libkrun" [3], another dynamic library that > allows programs to acquire virtualization-based process isolation > capabilites. The main user of "libkrun" is "crun", when built with > "--with-libkrun", an OCI runtime used by "podman". When all pieces are > in place, users can easily run containers with virtualization-based > isolation by adding some additional flags to the "podman" command > line. I have a COPR repository with pre-built alternative packages as > a demonstration [4]. > > There are a number of reasons why we can't use the kernel that ships > with Fedora: > > - We carry a small number of patches with minor changes that modify > the behavior of the kernel for this particular use case. Without > them, we can't provide an streamlined UX for running isolated > processes. Are these patches not headed upstream? How are these handled with regards to security updates for the kernel itself, how current do these patches run? The Fedora kernel tends to be updated once to twice a week for released versions of Fedora, and we typically have a number of CVEs flowing in. With this smaller kernel, some of those will not be relevant, but someone would need to keep up with them, determine if they are or are not, and apply them if so. Of course it might just be easier to just always build. > - We need an aggressive minimalist configuration to reduce the memory > footprint of each container/isolated process. There could be other ways to accomplish this. > - We need it to be bundled in a dynamic library, so their contents > are mapped into the process memory, enabling programs to switch > between namespaces without the need to carry the kernel binary with > them. The binary object also needs to be properly aligned to allow > direct injection into the KVM memory region without additional > copies. > > Given that "libkrunfw" bundles a kernel image that can't be used for > booting the system, would it be acceptable to package it in Fedora? > It does alleviate some of the concerns, there wouldn't be bugs filed against the kernel package where we have to figure out what kernel is being booted, etc. I am still very much concerned about how updates/security are handled in such a scenario though. Justin _______________________________________________ kernel mailing list -- kernel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to kernel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/kernel@xxxxxxxxxxxxxxxxxxxxxxx
