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ef1614edb2
Fixes: #7573
To enable this feature, build your rootfs using AGENT_POLICY=yes. The
default is AGENT_POLICY=no.
Building rootfs using AGENT_POLICY=yes has the following effects:
1. The kata-opa service gets included in the Guest image.
2. The agent gets built using AGENT_POLICY=yes.
After this patch, the shim calls SetPolicy if and only if a Policy
annotation is attached to the sandbox/pod. When creating a sandbox/pod
that doesn't have an attached Policy annotation:
1. If the agent was built using AGENT_POLICY=yes, the new sandbox uses
the default agent settings, that might include a default Policy too.
2. If the agent was built using AGENT_POLICY=no, the new sandbox is
executed the same way as before this patch.
Any SetPolicy calls from the shim to the agent fail if the agent was
built using AGENT_POLICY=no.
If the agent was built using AGENT_POLICY=yes:
1. The agent reads the contents of a default policy file during sandbox
start-up.
2. The agent then connects to the OPA service on localhost and sends
the default policy to OPA.
3. If the shim calls SetPolicy:
a. The agent checks if SetPolicy is allowed by the current
policy (the current policy is typically the default policy
mentioned above).
b. If SetPolicy is allowed, the agent deletes the current policy
from OPA and replaces it with the new policy it received from
the shim.
A typical new policy from the shim doesn't allow any future SetPolicy
calls.
4. For every agent rpc API call, the agent asks OPA if that call
should be allowed. OPA allows or not a call based on the current
policy, the name of the agent API, and the API call's inputs. The
agent rejects any calls that are rejected by OPA.
When building using AGENT_POLICY_DEBUG=yes, additional Policy logging
gets enabled in the agent. In particular, information about the inputs
for agent rpc API calls is logged in /tmp/policy.txt, on the Guest VM.
These inputs can be useful for investigating API calls that might have
been rejected by the Policy. Examples:
1. Load a failing policy file test1.rego on a different machine:
opa run --server --addr 127.0.0.1:8181 test1.rego
2. Collect the API inputs from Guest's /tmp/policy.txt and test on the
machine where the failing policy has been loaded:
curl -X POST http://localhost:8181/v1/data/agent_policy/CreateContainerRequest \
--data-binary @test1-inputs.json
Signed-off-by: Dan Mihai <dmihai@microsoft.com>
(cherry picked from commit ab829d1038)
Note: this is cherrypicked to help with the following:
- Provide a building block to continue experimenting with policy and identify issues at the earliest.
This is especially helpful for remote hypervisor (peer-pods) as currently we have no way to test
this feature and identify areas of improvements as part of merge to main.
- Provide a building building block to prototype and understand any potential gaps or integration
issues with the initdata specification discussed in the following issue - https://github.com/confidential-containers/confidential-containers/issues/171
There are no tests for this feature in CCv0 branch and you should use it at your own risk.
Signed-off-by: Pradipta Banerjee <pradipta.banerjee@gmail.com>