[v13] Prevent remote proxies from impersonating users from different clusters#33540
Merged
tigrato merged 2 commits intobranch/v13from Oct 16, 2023
Merged
[v13] Prevent remote proxies from impersonating users from different clusters#33540tigrato merged 2 commits intobranch/v13from
tigrato merged 2 commits intobranch/v13from
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This PR prevents root proxies from impersonating users from different clusters when accessing a leaf cluster.
During authentication, the proxy presents its certificate and sends the impersonation header.
A malicious attacker in possession of the root cluster proxy cert-key pair could bypass the root-leaf cluster permissions boundary by impersonating local users. This PR prevents that and remote proxies can only impersonate users belonging to their cluster.
KubeCSR Flow:
```mermaid
sequenceDiagram
ROOT PROXY->>+LEAF PROXY: Forward the request identity cert
LEAF PROXY ->> LEAF AUTH SRV: Sign identity via KubeCSR
LEAF AUTH SRV -->> LEAF PROXY: Identity cert
LEAF PROXY ->> LEAF KUBE SERVICE: Forward the request using cert
LEAF KUBE SERVICE -->> LEAF PROXY: Return response
LEAF PROXY -->> ROOT PROXY: Return response
```
Impersonation Flow:
```mermaid
sequenceDiagram
ROOT PROXY->>+LEAF PROXY: Forward the request identity by Impersonating
LEAF PROXY ->> LEAF KUBE SERVICE: Forward the request identity by Impersonating
LEAF KUBE SERVICE -->> LEAF PROXY: Return response
LEAF PROXY -->> ROOT PROXY: Return response
```
Fixes gravitational/teleport-private#968
Signed-off-by: Tiago Silva <tiago.silva@goteleport.com>
rosstimothy
approved these changes
Oct 16, 2023
r0mant
approved these changes
Oct 16, 2023
Merged
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Backport #33536 to branch/v13