minio/cmd/config/policy/opa/config.go

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/*
* MinIO Cloud Storage, (C) 2018-2019 MinIO, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package opa
import (
"bytes"
"encoding/json"
"io"
"io/ioutil"
"net/http"
"github.com/minio/minio/cmd/config"
"github.com/minio/minio/pkg/env"
iampolicy "github.com/minio/minio/pkg/iam/policy"
xnet "github.com/minio/minio/pkg/net"
)
// Env IAM OPA URL
const (
URL = "url"
AuthToken = "auth_token"
EnvPolicyOpaURL = "MINIO_POLICY_OPA_URL"
EnvPolicyOpaAuthToken = "MINIO_POLICY_OPA_AUTH_TOKEN"
)
// DefaultKVS - default config for OPA config
var (
DefaultKVS = config.KVS{
config.KV{
Key: URL,
Value: "",
},
config.KV{
Key: AuthToken,
Value: "",
},
}
)
// Args opa general purpose policy engine configuration.
type Args struct {
URL *xnet.URL `json:"url"`
AuthToken string `json:"authToken"`
Transport http.RoundTripper `json:"-"`
CloseRespFn func(r io.ReadCloser) `json:"-"`
}
// Validate - validate opa configuration params.
func (a *Args) Validate() error {
req, err := http.NewRequest(http.MethodPost, a.URL.String(), bytes.NewReader([]byte("")))
if err != nil {
return err
}
req.Header.Set("Content-Type", "application/json")
if a.AuthToken != "" {
req.Header.Set("Authorization", a.AuthToken)
}
client := &http.Client{Transport: a.Transport}
resp, err := client.Do(req)
if err != nil {
return err
}
defer a.CloseRespFn(resp.Body)
return nil
}
// UnmarshalJSON - decodes JSON data.
func (a *Args) UnmarshalJSON(data []byte) error {
// subtype to avoid recursive call to UnmarshalJSON()
type subArgs Args
var so subArgs
if err := json.Unmarshal(data, &so); err != nil {
return err
}
oa := Args(so)
if oa.URL == nil || oa.URL.String() == "" {
*a = oa
return nil
}
*a = oa
return nil
}
// Opa - implements opa policy agent calls.
type Opa struct {
args Args
client *http.Client
}
// Enabled returns if opa is enabled.
func Enabled(kvs config.KVS) bool {
return kvs.Get(URL) != ""
}
// LookupConfig lookup Opa from config, override with any ENVs.
func LookupConfig(kv config.KVS, transport *http.Transport, closeRespFn func(io.ReadCloser)) (Args, error) {
args := Args{}
if err := config.CheckValidKeys(config.PolicyOPASubSys, kv, DefaultKVS); err != nil {
return args, err
}
opaURL := env.Get(EnvIamOpaURL, "")
if opaURL == "" {
opaURL = env.Get(EnvPolicyOpaURL, kv.Get(URL))
if opaURL == "" {
return args, nil
}
}
authToken := env.Get(EnvIamOpaAuthToken, "")
if authToken == "" {
authToken = env.Get(EnvPolicyOpaAuthToken, kv.Get(AuthToken))
}
u, err := xnet.ParseHTTPURL(opaURL)
if err != nil {
return args, err
}
args = Args{
URL: u,
AuthToken: authToken,
Transport: transport,
CloseRespFn: closeRespFn,
}
if err = args.Validate(); err != nil {
return args, err
}
return args, nil
}
// New - initializes opa policy engine connector.
func New(args Args) *Opa {
// No opa args.
if args.URL == nil || args.URL.Scheme == "" && args.AuthToken == "" {
return nil
}
return &Opa{
args: args,
client: &http.Client{Transport: args.Transport},
}
}
// IsAllowed - checks given policy args is allowed to continue the REST API.
func (o *Opa) IsAllowed(args iampolicy.Args) (bool, error) {
if o == nil {
return false, nil
}
// OPA input
body := make(map[string]interface{})
body["input"] = args
inputBytes, err := json.Marshal(body)
if err != nil {
return false, err
}
req, err := http.NewRequest(http.MethodPost, o.args.URL.String(), bytes.NewReader(inputBytes))
if err != nil {
return false, err
}
req.Header.Set("Content-Type", "application/json")
if o.args.AuthToken != "" {
req.Header.Set("Authorization", o.args.AuthToken)
}
resp, err := o.client.Do(req)
if err != nil {
return false, err
}
defer o.args.CloseRespFn(resp.Body)
// Read the body to be saved later.
opaRespBytes, err := ioutil.ReadAll(resp.Body)
if err != nil {
return false, err
}
// Handle large OPA responses when OPA URL is of
// form http://localhost:8181/v1/data/httpapi/authz
type opaResultAllow struct {
Result struct {
Allow bool `json:"allow"`
} `json:"result"`
}
// Handle simpler OPA responses when OPA URL is of
// form http://localhost:8181/v1/data/httpapi/authz/allow
type opaResult struct {
Result bool `json:"result"`
}
respBody := bytes.NewReader(opaRespBytes)
var result opaResult
if err = json.NewDecoder(respBody).Decode(&result); err != nil {
respBody.Seek(0, 0)
var resultAllow opaResultAllow
if err = json.NewDecoder(respBody).Decode(&resultAllow); err != nil {
return false, err
}
return resultAllow.Result.Allow, nil
}
return result.Result, nil
}