/
policy.go
201 lines (172 loc) · 5.14 KB
/
policy.go
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// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package policy
import (
"encoding/json"
"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"`
Groups []string `json:"groups"`
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 Errorf("invalid version '%v'", policy.Version)
}
for _, statement := range policy.Statements {
if err := statement.isValid(); err != nil {
return err
}
}
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))
}
// Merge merges two policies documents and drop
// duplicate statements if any.
func (policy Policy) Merge(input Policy) Policy {
var mergedPolicy Policy
if policy.Version != "" {
mergedPolicy.Version = policy.Version
} else {
mergedPolicy.Version = input.Version
}
for _, st := range policy.Statements {
mergedPolicy.Statements = append(mergedPolicy.Statements, st.Clone())
}
for _, st := range input.Statements {
mergedPolicy.Statements = append(mergedPolicy.Statements, st.Clone())
}
mergedPolicy.dropDuplicateStatements()
return mergedPolicy
}
func (policy *Policy) dropDuplicateStatements() {
redo:
for i := range policy.Statements {
for _, statement := range policy.Statements[i+1:] {
if !policy.Statements[i].Equals(statement) {
continue
}
policy.Statements = append(policy.Statements[:i], policy.Statements[i+1:]...)
goto redo
}
}
}
// 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
}
p.dropDuplicateStatements()
*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, Errorf("%w", err)
}
err := policy.Validate(bucketName)
return &policy, err
}
// Equals returns true if the two policies are identical
func (policy *Policy) Equals(p Policy) bool {
if policy.ID != p.ID || policy.Version != p.Version {
return false
}
if len(policy.Statements) != len(p.Statements) {
return false
}
for i, st := range policy.Statements {
if !p.Statements[i].Equals(st) {
return false
}
}
return true
}