Tree-signing in Gentoo and recent research into Package Manager Security
So on Slashdot today, there was a link to the latest research into Package manager security. Specifically, their focus was on defeating signed packages by use of malicious mirrors and replay attacks of signed content. Recording the source of client requests, and possibly denying specific security updates (having an older tree that doesn't contain the security updates).
This plays into some of my long-ongoing tree-signing research in Gentoo. The GLEPs with the exception of 02 and 03 have been mailed to the GLEP editors as well as the portage-dev mailing list, and will be going to the gentoo-dev mailing list after the GLEP editors have reviewed them.
For dealing with the new issues raised by Cappos et al, at Gentoo we are really lucky to have our own infra maintained hardened rotation of mirrors at rsync://rsync.gentoo.org/ in addition to the community mirrors at rsync://rsync$N.$CC.gentoo.org/. Nobody using just the infra-maintained mirrors (barring MITM attacks) would be vulnerable to the new attacks described by Cappos, however those using a community-maintained mirror could be.
Using the main mirrors for new signing purposes, this will enable us to deliver the new MetaManifests reliably via our own infrastructure, even when the user has a community mirror for their actual tree content. The actual changes to the GLEP for this weren't very big at all. Just a timestamp header inside the signed area, as well as distributing the MetaManifests via a trusted medium.
As a minor side note on the infra-maintained rsync.gentoo.org rotation, this would be a good time to consider sponsering a box to Gentoo for that purpose. Each of the 5 existing boxes in the rotation does 50-65GiB of traffic every day - averaging to 6.5Mbit/sec, over a 24-hour period. These boxes are bandwidth, memory and CPU intensive, however they don't hit disk very hard (we serve the trees directly from memory). 4GiB RAM, 2+ 64-bit processors (single core or dual core is fine), ~16GiB of disk (optional: software RAID1 is nice for avoiding downtime, and fancy fast disks aren't needed). We need a serial console or KVM to install it securely - you just boot the box to a livecd, get the access details to infra, we install it from there with our own stage4 tarball that links into cfengine. The machine continues to be owned by the sponsor, in your data centre.
Syndicated 2008-07-11 01:59:02 from Move along, nothing to read