On Mon, 2021-11-29 at 09:30 -0500, Stefan Berger wrote: > On 11/29/21 09:10, James Bottomley wrote: > > On Mon, 2021-11-29 at 08:53 -0500, Stefan Berger wrote: > > > On 11/29/21 07:50, James Bottomley wrote: > > > > On Sun, 2021-11-28 at 22:58 -0600, Serge E. Hallyn wrote: > > > > > On Sat, Nov 27, 2021 at 04:45:49PM +0000, James Bottomley > > > > > wrote: > > > > > > Currently we get one entry in the IMA log per unique file > > > > > > event. So, if you have a measurement policy and it > > > > > > measures a particular binary it will not get measured again > > > > > > if it is subsequently executed. For Namespaced IMA, the > > > > > > correct behaviour seems to be to log once per inode per > > > > > > namespace (so every unique execution in a namespace gets a > > > > > > separate log entry). Since logging once per inode per > > > > > > namespace is > > > > > I suspect I'll need to do a more in depth reading of the > > > > > existing code, but I'll ask the lazy question anyway (since > > > > > you say "the correct behavior seems to be") - is it actually > > > > > important that files which were appraised under a parent > > > > > namespace's policy already should be logged again? > > > > I think so. For a couple of reasons, assuming the namespace > > > > eventually gets its own log entries, which the next incremental > > > > patch proposed to do by virtualizing the securityfs > > > > entries. If you don't do this: > > > To avoid duplicate efforts, an implementation of a virtualized > > > securityfs is in this series here: > > > > > > https://github.com/stefanberger/linux-ima-namespaces/commits/v5.15%2Bimans.20211119.v3 > > > > > > It starts with 'securityfs: Prefix global variables with > > > secruityfs_' > > That's quite a big patch series. I already actually implemented > > this as part of the RFC for getting the per namespace measurement > > log. The attached is basically what I did. > > I know it's big. I tried to avoid having to bind-mount the system- > wide single securityfs into the container and inherit all the other > security subsystems' files and directories (evm, TPM, safesetid, > apparmor, tomoyo [ > https://elixir.bootlin.com/linux/latest/C/ident/securityfs_create_dir > > ]) and instead have a 'view' that is a bit more restricted to those > subsystems that are namespaced. The securityfs_ns I created can be > mounted into each user namespace individually and only shows what > you're supposed to see without other filesystem tricks to hide files > or so. It should be future-extensible for other subsystem to register > themselves there if they have something to show to the user. Using F_USER_NS for this is certainly what it was designed for. I don't think size is a problem as long as it's right sized to perform the required function. I usually find it easier to oversimplify and work up, but that's certainly not the only approach. James
