On 23/05/2023 23:12, Paul Moore wrote:
On Tue, May 23, 2023 at 2:13 AM Jeff Xu <jeffxu@xxxxxxxxxxxx> wrote:
On Mon, May 22, 2023 at 12:56 PM Paul Moore <paul@xxxxxxxxxxxxxx> wrote:
On Thu, May 18, 2023 at 5:26 PM Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote:
On 5/18/2023 1:45 PM, Shervin Oloumi wrote:
Adds a new getprocattr hook function to the Landlock LSM, which tracks
the landlocked state of the process. This is invoked when user-space
reads /proc/[pid]/attr/domain
Please don't add a Landlock specific entry directly in the attr/
directory. Add it only to attr/landlock.
Also be aware that the LSM maintainer (Paul Moore) wants to move
away from the /proc/.../attr interfaces in favor of a new system call,
which is in review.
What Casey said above.
There is still some uncertainty around timing, and if we're perfectly
honest, acceptance of the new syscalls at the Linus level, but yes, I
would very much like to see the LSM infrastructure move away from
procfs and towards a syscall API. Part of the reasoning is that the
current procfs API is ill-suited to handle the multiple, stacked LSMs
and the other part being the complexity of procfs in a namespaced
system. If the syscall API is ultimately rejected, we will need to
revisit the idea of a procfs API, but even then I think we'll need to
make some changes to the current approach.
As I believe we are in the latter stages of review for the syscall
API, perhaps you could take a look and ensure that the current
proposed API works for what you are envisioning with Landlock?
I agree, and since the LSM syscalls are almost ready that should not
change much the timing. In fact, extending these syscalls might be
easier than tweaking the current procfs/attr API for Landlock specific
requirements (e.g. scoped visibility). We should ensure that these
syscalls would be a good fit to return file descriptors, but in the
short term we only need to know if a process is landlocked or not, so a
raw return value (0 or -errno) will be enough.
Mentioning in the LSM syscalls patch series that they may deal with (and
return) file descriptors could help API reviewers though.
Which review/patch to look for the proposed API ?
See Casey's reply if you haven't already. You can also find the LSM
list archived on lore.kernel.org; that is probably the best way to
track LSM development if you don't want to subscribe to the list.
* https://lore.kernel.org/linux-security-module
I guess ChromeOS will need to backport to 5.10 when the proposal is accepted.
Maybe? Distro specific backports aren't generally on-topic for the
upstream Linux mailing lists, especially large commercial distros with
plenty of developers to take care of things like that.
Backporting the LSM syscall patch series will create conflicts but they
should be manageable and the series should be quite standalone. You'll
need to understand the changes to get a clean backport, so reviewing the
current proposal is a good opportunity to be ready and to catch
potential future issues.
