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minio/pkg/policy/statement.go

156 lines
4.1 KiB

/*
* MinIO Cloud Storage, (C) 2018 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 policy
import (
"encoding/json"
"fmt"
"strings"
"github.com/minio/minio/pkg/policy/condition"
)
// Statement - policy statement.
type Statement struct {
SID ID `json:"Sid,omitempty"`
Effect Effect `json:"Effect"`
Principal Principal `json:"Principal"`
Actions ActionSet `json:"Action"`
Resources ResourceSet `json:"Resource"`
Conditions condition.Functions `json:"Condition,omitempty"`
}
// IsAllowed - checks given policy args is allowed to continue the Rest API.
func (statement Statement) IsAllowed(args Args) bool {
check := func() bool {
if !statement.Principal.Match(args.AccountName) {
return false
}
if !statement.Actions.Contains(args.Action) {
return false
}
resource := args.BucketName
if args.ObjectName != "" {
if !strings.HasPrefix(args.ObjectName, "/") {
resource += "/"
}
resource += args.ObjectName
}
if !statement.Resources.Match(resource, args.ConditionValues) {
return false
}
return statement.Conditions.Evaluate(args.ConditionValues)
}
return statement.Effect.IsAllowed(check())
}
// isValid - checks whether statement is valid or not.
func (statement Statement) isValid() error {
if !statement.Effect.IsValid() {
return fmt.Errorf("invalid Effect %v", statement.Effect)
}
if !statement.Principal.IsValid() {
return fmt.Errorf("invalid Principal %v", statement.Principal)
}
if len(statement.Actions) == 0 {
return fmt.Errorf("Action must not be empty")
}
if len(statement.Resources) == 0 {
return fmt.Errorf("Resource must not be empty")
}
for action := range statement.Actions {
if action.isObjectAction() {
if !statement.Resources.objectResourceExists() {
return fmt.Errorf("unsupported Resource found %v for action %v", statement.Resources, action)
}
} else {
if !statement.Resources.bucketResourceExists() {
return fmt.Errorf("unsupported Resource found %v for action %v", statement.Resources, action)
}
}
keys := statement.Conditions.Keys()
keyDiff := keys.Difference(actionConditionKeyMap[action])
if !keyDiff.IsEmpty() {
return fmt.Errorf("unsupported condition keys '%v' used for action '%v'", keyDiff, action)
}
}
return nil
}
// MarshalJSON - encodes JSON data to Statement.
func (statement Statement) MarshalJSON() ([]byte, error) {
if err := statement.isValid(); err != nil {
return nil, err
}
// subtype to avoid recursive call to MarshalJSON()
type subStatement Statement
ss := subStatement(statement)
return json.Marshal(ss)
}
// UnmarshalJSON - decodes JSON data to Statement.
func (statement *Statement) UnmarshalJSON(data []byte) error {
// subtype to avoid recursive call to UnmarshalJSON()
type subStatement Statement
var ss subStatement
if err := json.Unmarshal(data, &ss); err != nil {
return err
}
s := Statement(ss)
if err := s.isValid(); err != nil {
return err
}
*statement = s
return nil
}
// Validate - validates Statement is for given bucket or not.
func (statement Statement) Validate(bucketName string) error {
if err := statement.isValid(); err != nil {
return err
}
return statement.Resources.Validate(bucketName)
}
// NewStatement - creates new statement.
func NewStatement(effect Effect, principal Principal, actionSet ActionSet, resourceSet ResourceSet, conditions condition.Functions) Statement {
return Statement{
Effect: effect,
Principal: principal,
Actions: actionSet,
Resources: resourceSet,
Conditions: conditions,
}
}