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Copy pathpolicy.go
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176 lines (146 loc) · 4.42 KB
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/*
* 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"
"io"
)
// DefaultVersion - default policy version as per AWS S3 specification.
const DefaultVersion = "2012-10-17"
// Args - arguments to policy to check whether it is allowed
type Args struct {
AccountName string `json:"account"`
Action Action `json:"action"`
BucketName string `json:"bucket"`
ConditionValues map[string][]string `json:"conditions"`
IsOwner bool `json:"owner"`
ObjectName string `json:"object"`
}
// Policy - bucket policy.
type Policy struct {
ID ID `json:"ID,omitempty"`
Version string
Statements []Statement `json:"Statement"`
}
// IsAllowed - checks given policy args is allowed to continue the Rest API.
func (policy Policy) IsAllowed(args Args) bool {
// Check all deny statements. If any one statement denies, return false.
for _, statement := range policy.Statements {
if statement.Effect == Deny {
if !statement.IsAllowed(args) {
return false
}
}
}
// For owner, its allowed by default.
if args.IsOwner {
return true
}
// Check all allow statements. If any one statement allows, return true.
for _, statement := range policy.Statements {
if statement.Effect == Allow {
if statement.IsAllowed(args) {
return true
}
}
}
return false
}
// IsEmpty - returns whether policy is empty or not.
func (policy Policy) IsEmpty() bool {
return len(policy.Statements) == 0
}
// isValid - checks if Policy is valid or not.
func (policy Policy) isValid() error {
if policy.Version != DefaultVersion && policy.Version != "" {
return fmt.Errorf("invalid version '%v'", policy.Version)
}
for _, statement := range policy.Statements {
if err := statement.isValid(); err != nil {
return err
}
}
for i := range policy.Statements {
for _, statement := range policy.Statements[i+1:] {
principals := policy.Statements[i].Principal.Intersection(statement.Principal)
if principals.IsEmpty() {
continue
}
actions := policy.Statements[i].Actions.Intersection(statement.Actions)
if len(actions) == 0 {
continue
}
resources := policy.Statements[i].Resources.Intersection(statement.Resources)
if len(resources) == 0 {
continue
}
if policy.Statements[i].Conditions.String() != statement.Conditions.String() {
continue
}
return fmt.Errorf("duplicate principal %v, actions %v, resouces %v found in statements %v, %v",
principals, actions, resources, policy.Statements[i], statement)
}
}
return nil
}
// MarshalJSON - encodes Policy to JSON data.
func (policy Policy) MarshalJSON() ([]byte, error) {
if err := policy.isValid(); err != nil {
return nil, err
}
// subtype to avoid recursive call to MarshalJSON()
type subPolicy Policy
return json.Marshal(subPolicy(policy))
}
// UnmarshalJSON - decodes JSON data to Policy.
func (policy *Policy) UnmarshalJSON(data []byte) error {
// subtype to avoid recursive call to UnmarshalJSON()
type subPolicy Policy
var sp subPolicy
if err := json.Unmarshal(data, &sp); err != nil {
return err
}
p := Policy(sp)
if err := p.isValid(); err != nil {
return err
}
*policy = p
return nil
}
// Validate - validates all statements are for given bucket or not.
func (policy Policy) Validate(bucketName string) error {
if err := policy.isValid(); err != nil {
return err
}
for _, statement := range policy.Statements {
if err := statement.Validate(bucketName); err != nil {
return err
}
}
return nil
}
// ParseConfig - parses data in given reader to Policy.
func ParseConfig(reader io.Reader, bucketName string) (*Policy, error) {
var policy Policy
decoder := json.NewDecoder(reader)
decoder.DisallowUnknownFields()
if err := decoder.Decode(&policy); err != nil {
return nil, err
}
err := policy.Validate(bucketName)
return &policy, err
}