Authentication with the API server

Kuma exposes API server on ports 5681 and 5682 (protected by TLS).

An authenticated user can be authorized to execute administrative actions such as

• Managing administrative resources like Kuma Secrets on Universal
• Generating user token, data plane proxy token, zone ingress token, zone token

User token

A user token is a signed JWT token that contains

• The name of the user
• The list of groups that a user belongs to
• Expiration date of the token

Groups

A user can be a part of many groups. Kuma adds two groups to a user automatically:

• authenticated users are a part of mesh-system:authenticated.
• unauthenticated users are part of mesh-system:unauthenticated.

Admin user token

Kuma creates an admin user token on the first start of the control plane. The admin user token is a user token issued for user mesh-system:admin that belongs to mesh-system:admin group. This group is authorized by default to execute all administrative operations.

Generate user tokens

You can generate user tokens only when you provide the credentials of a user authorized to generate user tokens . kumactl configured with admin user token extracted in the preceding section is authorized to do it.

kumactl generate user-token \
  --name john \
  --group team-a \
  --valid-for 24h

or you can use API

curl localhost:5681/tokens/user \
  -H'authorization: Bearer eyJhbGc...' \
  -H'content-type: application/json' \
  --data '{"name": "john","groups": ["team-a"], "validFor": "24h"}' 

Explore an example token

You can decode the tokens to validate the signature or explore details.

For example, run:

kumactl generate user-token \
  --name john \
  --group team-a \
  --valid-for 24h

which returns:

eyJhbGciOiJSUzI1NiIsImtpZCI6IjEiLCJ0eXAiOiJKV1QifQ.eyJOYW1lIjoiam9obiIsIkdyb3VwcyI6WyJ0ZWFtLWEiXSwiZXhwIjoxNjM2ODExNjc0LCJuYmYiOjE2MzY3MjQ5NzQsImlhdCI6MTYzNjcyNTI3NCwianRpIjoiYmYzZDBiMmUtZDg0MC00Y2I2LWJmN2MtYjkwZjU0MzkxNDY4In0.XsaPcQ5wVzRLs4o1FWywf6kw4r2ceyLGxYO8EbyA0fAxU6BPPRsW71ueD8ZlS4JlD4UrVtQQ7LG-z_nIxlDRAYhx4mmHnSjtqWZIsVS13QRrm41zccZ0SKHYxGvWMW4IkGwUbA0UZOJGno8vbpI6jTGfY9bmof5FpJJAj_sf99jCaI1H_n3n5UxtwKVN7dXXD82r6axj700jgQD-2O8gnejzlTjZkBpPF_lGnlBbd39S34VNwT0UlvRJLmCRdfh5EL24dFt0tyzQqDG2gE1RuGvTV9LOT77ZsjfMP9CITICivF6Z7uqvlOYal10jd5gN0A6w6KSI8CCaDLmVgUHvAw

Paste the token into the UI at jwt.io, or use jwt-cli tool

kumactl generate user-token --name=john --group=team-a --valid-for=24h | jwt

To verify on jwt.io:

https://jwt.io/#id_token=eyJhbGciOiJSUzI1NiIsImtpZCI6IjEiLCJ0eXAiOiJKV1QifQ.eyJOYW1lIjoiam9obiIsIkdyb3VwcyI6WyJ0ZWFtLWEiXSwiZXhwIjoxNjM2ODExNjc0LCJuYmYiOjE2MzY3MjQ5NzQsImlhdCI6MTYzNjcyNTI3NCwianRpIjoiYmYzZDBiMmUtZDg0MC00Y2I2LWJmN2MtYjkwZjU0MzkxNDY4In0.XsaPcQ5wVzRLs4o1FWywf6kw4r2ceyLGxYO8EbyA0fAxU6BPPRsW71ueD8ZlS4JlD4UrVtQQ7LG-z_nIxlDRAYhx4mmHnSjtqWZIsVS13QRrm41zccZ0SKHYxGvWMW4IkGwUbA0UZOJGno8vbpI6jTGfY9bmof5FpJJAj_sf99jCaI1H_n3n5UxtwKVN7dXXD82r6axj700jgQD-2O8gnejzlTjZkBpPF_lGnlBbd39S34VNwT0UlvRJLmCRdfh5EL24dFt0tyzQqDG2gE1RuGvTV9LOT77ZsjfMP9CITICivF6Z7uqvlOYal10jd5gN0A6w6KSI8CCaDLmVgUHvAw

✻ Header
{
  "alg": "RS256",
  "kid": "1",
  "typ": "JWT"
}

✻ Payload
{
  "Name": "john",
  "Groups": [
    "team-a"
  ],
  "exp": 1636811674,
  "nbf": 1636724974,
  "iat": 1636725274,
  "jti": "bf3d0b2e-d840-4cb6-bf7c-b90f54391468"
}
   Issued At: 1636725274 11/12/2021, 2:54:34 PM
   Not Before: 1636724974 11/12/2021, 2:49:34 PM
   Expiration Time: 1636811674 11/13/2021, 2:54:34 PM

✻ Signature XsaPcQ5wVzRLs4o1FWywf6kw4r2ceyLGxYO8EbyA0fAxU6BPPRsW71ueD8ZlS4JlD4UrVtQQ7LG-z_nIxlDRAYhx4mmHnSjtqWZIsVS13QRrm41zccZ0SKHYxGvWMW4IkGwUbA0UZOJGno8vbpI6jTGfY9bmof5FpJJAj_sf99jCaI1H_n3n5UxtwKVN7dXXD82r6axj700jgQD-2O8gnejzlTjZkBpPF_lGnlBbd39S34VNwT0UlvRJLmCRdfh5EL24dFt0tyzQqDG2gE1RuGvTV9LOT77ZsjfMP9CITICivF6Z7uqvlOYal10jd5gN0A6w6KSI8CCaDLmVgUHvAw

Token revocation

Kuma doesn’t keep the list of issued tokens. To invalidate the token, you can add it to a revocation list. Every user token has its own ID. As you saw in the previous section, it’s available in payload under jti key. To revoke tokens, specify list of revoked IDs separated by , and store it as GlobalSecret named user-token-revocations

REVOCATIONS=$(echo '0e120ec9-6b42-495d-9758-07b59fe86fb9' | base64) && echo "apiVersion: v1
kind: Secret
metadata:
  name: user-token-revocations
  namespace: kuma-system 
data:
  value: $REVOCATIONS
type: system.kuma.io/global-secret" | kubectl apply -f -

echo "
type: GlobalSecret
name: user-token-revocations
data: " | kumactl apply --var revocations=$(echo '0e120ec9-6b42-495d-9758-07b59fe86fb9' | base64) -f -

Signing key

A user token is signed by a signing key that’s autogenerated on the first start of the control plane. The signing key is a 2048-bit RSA key stored as a GlobalSecret with a name that looks like user-token-signing-key-{serialNumber}.

Signing key rotation

If the signing key is compromised, you must rotate it including all the tokens that were signed by it.

1. Generate a new signing key

   Make sure to generate the new signing key with a serial number greater than the serial number of the current signing key.

   • Kubernetes
   • Universal

   Check what’s the current highest serial number.

      kubectl get secrets -n kuma-system --field-selector='type=system.kuma.io/global-secret'
      NAME                          TYPE                           DATA   AGE
      user-token-signing-key-1   system.kuma.io/global-secret   1      25m

   In this case, the highest serial number is 1. Generate a new signing key with a serial number of 2

      TOKEN="$(kumactl generate signing-key)" && echo "
      apiVersion: v1
      data:
        value: $TOKEN
      kind: Secret
      metadata:
        name: user-token-signing-key-2
        namespace: kuma-system
      type: system.kuma.io/global-secret
      " | kubectl apply -f - 

   Check what’s the current highest serial number.

      kumactl get global-secrets
      NAME                             AGE
      user-token-signing-key-1   36m

   In this case, the highest serial number is 1. Generate a new signing key with a serial number of 2

      echo "
      type: GlobalSecret
      name: user-token-signing-key-2
      data: " | kumactl apply --var key=$(kumactl generate signing-key) -f -

2. Regenerate user tokens

   Create new user tokens. Tokens are always signed by the signing key with the highest serial number. Starting from now, tokens signed by either new or old signing key are valid.

3. Remove the old signing key

   • Kubernetes
   • Universal

      kubectl delete secret user-token-signing-key-1 -n kuma-system

      kumactl delete global-secret user-token-signing-key-1

   All new requests to the control plane now require tokens signed with the new signing key.

Disabling bootstrap of the admin user token

You can remove the default admin user token from the storage and prevent it from being recreated. Keep in mind that even if you remove the admin user token, the signing key is still present. A malicious actor that acquires the signing key, can generate an admin token.

Offline token issuing

In addition to the regular flow of generating signing keys, storing them in secret, and using them to sign tokens on the control plane, Kuma also offers offline signing of tokens. In this flow, you can generate a pair of public and private keys and configure the control plane only with public keys for token verification. You can generate all the tokens without running the control plane.

The advantages of this mode are:

• easier, more reproducible deployments of the control plane, and more in line with GitOps.
• potentially more secure setup, because the control plane does not have access to the private keys.

Here’s how to use offline issuing

1. Generate a pair of signing keys

   The following commands generate standard RSA key of 2048 bits and outputs it in PEM-encoded format. You can use any external tool to generate a pair of keys.

   kumactl generate signing-key --format=pem > /tmp/key-private.pem
   kumactl generate public-key --signing-key-path=/tmp/key-private.pem > /tmp/key-public.pem
   

   The result should be similar to this output

   cat /tmp/key-private.pem /tmp/key-public.pem 
   -----BEGIN RSA PRIVATE KEY-----
   MIIEpAIBAAKCAQEAsS61a79gC4mkr2Ltwi09ajakLyUR8YTkJWzZE805EtTkEn/r
   ...
   htKtzsYA7yGlt364IuDybrP+PlPMSK9cQAmWRRZIcBNsKOODkAgKFA==
   -----END RSA PRIVATE KEY-----
   -----BEGIN RSA PUBLIC KEY-----
   MIIBCgKCAQEAsS61a79gC4mkr2Ltwi09ajakLyUR8YTkJWzZE805EtTkEn/rL2u/
   ...
   se7sx2Pt/NPbWFFTMGVFm3A1ueTUoorW+wIDAQAB
   -----END RSA PUBLIC KEY----- 
   

2. Configure the control plane with public key

   Configure a control plane with the following settings

   apiServer:
     authn:
       type: tokens
       tokens:
         enableIssuer: false # disable control plane token issuer that uses secrets
         validator:
           useSecrets: false # do not use signing key stored in secrets to validate the token
           publicKeys:
           - kid: "key-1"
             key: |
               -----BEGIN RSA PUBLIC KEY-----
               MIIBCgKCAQEAsS61a79gC4mkr2Ltwi09ajakLyUR8YTkJWzZE805EtTkEn/rL2u/
               ...
               se7sx2Pt/NPbWFFTMGVFm3A1ueTUoorW+wIDAQAB
               -----END RSA PUBLIC KEY-----
   

3. Use the private key to issue tokens offline

   The command is the same as with online signing, but with two additional arguments:

   • --kid - ID of the key that should be used to validate the token. This should match kid specified in the control plane configuration.
   • --signing-key-path - path to a PEM-encoded private key.

   kumactl generate user-token \
     --name john.doe@example.com \
     --group users \
     --valid-for 24h \
     --signing-key-path /tmp/key-private.pem \
     --kid key-1
   

   You can also use any external system that can issue JWT tokens using RS256 signing method with the following claims:

   • Name (string) - the name of the user
   • Groups ([]string) - list of user groups

Migration

You can use both offline and online issuing by keeping apiServer.authn.tokens.enableIssuer to true. You can use both secrets and public key static config validators by keeping apiServer.authn.tokens.validator.useSecrets to true.

Management

Token revocation works the same when using both online and offline issuing.

Signing key rotation works similarly:

• generate another pair of signing keys
• configure a control plane with old and new public keys
• regenerate tokens for all existing users with the new private key
• remove the old public key from the configuration

Admin client certificates

This section describes the alternative way of authenticating to API Server.

To use admin client certificates, set KUMA_API_SERVER_AUTHN_TYPE to adminClientCerts.

All users that provide client certificate are authenticated as a user with the name mesh-system:admin that belongs to group mesh-system:admin.

Usage

1. Generate client certificates by using kumactl

   kumactl generate tls-certificate --type=client \
     --cert-file=/tmp/tls.crt \
     --key-file=/tmp/tls.key
   

2. Configure the control plane with client certificates

   • Kubernetes (kumactl)
   • Kubernetes (HELM)
   • Universal

   Create a secret in the namespace in which control plane is installed

      kubectl create secret generic api-server-client-certs -n kuma-system \
        --from-file=client1.pem=/tmp/tls.crt \

   You can provide as many client certificates as you want. Remember to only provide certificates without keys.

   Point to this secret when installing Kuma

      kumactl install control-plane \
        --tls-api-server-client-certs-secret=api-server-client-certs

   Create a secret in the namespace in which control plane is installed

      kubectl create secret generic api-server-client-certs -n kuma-system \
        --from-file=client1.pem=/tmp/tls.crt \

   You can provide as many client certificates as you want. Remember to only provide certificates without keys.

   Set controlPlane.tls.apiServer.clientCertsSecretName to api-server-client-certs via HELM

   Put all the certificates in one directory

      mkdir /opt/client-certs
      cp /tmp/tls.crt /opt/client-certs/client1.pem 

   All client certificates must end with .pem extension. Remember to only provide certificates without keys.

   Configure control plane by pointing to this directory

      KUMA_API_SERVER_AUTH_CLIENT_CERTS_DIR=/opt/client-certs \
        kuma-cp run

3. Configure kumactl with valid client certificate

   kumactl config control-planes add \
     --name=<NAME>
     --address=https://<KUMA_CP_DNS_NAME>:5682 \
     --client-cert-file=/tmp/tls.crt \
     --client-key-file=/tmp/tls.key \
     --ca-cert-file=/tmp/ca.crt
   

   If you want to skip CP verification, use --skip-verify instead of --ca-cert-file.

Multizone

In a multizone setup, users execute a majority of actions on the global control plane. However, some actions like generating dataplane tokens are available on the zone control plane. The global control plane doesn’t propagate authentication credentials to the zone control plane. You can set up consistent user tokens across the whole setup by manually copying signing key from global to zone control planes.