178 lines
4.4 KiB
Go
178 lines
4.4 KiB
Go
/*
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* MinIO Cloud Storage, (C) 2018 MinIO, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package policy
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import (
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"encoding/json"
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"io"
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)
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// DefaultVersion - default policy version as per AWS S3 specification.
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const DefaultVersion = "2012-10-17"
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// Args - arguments to policy to check whether it is allowed
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type Args struct {
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AccountName string `json:"account"`
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Action Action `json:"action"`
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BucketName string `json:"bucket"`
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ConditionValues map[string][]string `json:"conditions"`
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IsOwner bool `json:"owner"`
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ObjectName string `json:"object"`
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}
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// Policy - bucket policy.
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type Policy struct {
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ID ID `json:"ID,omitempty"`
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Version string
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Statements []Statement `json:"Statement"`
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}
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// IsAllowed - checks given policy args is allowed to continue the Rest API.
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func (policy Policy) IsAllowed(args Args) bool {
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// Check all deny statements. If any one statement denies, return false.
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for _, statement := range policy.Statements {
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if statement.Effect == Deny {
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if !statement.IsAllowed(args) {
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return false
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}
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}
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}
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// For owner, its allowed by default.
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if args.IsOwner {
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return true
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}
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// Check all allow statements. If any one statement allows, return true.
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for _, statement := range policy.Statements {
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if statement.Effect == Allow {
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if statement.IsAllowed(args) {
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return true
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}
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}
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}
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return false
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}
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// IsEmpty - returns whether policy is empty or not.
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func (policy Policy) IsEmpty() bool {
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return len(policy.Statements) == 0
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}
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// isValid - checks if Policy is valid or not.
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func (policy Policy) isValid() error {
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if policy.Version != DefaultVersion && policy.Version != "" {
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return Errorf("invalid version '%v'", policy.Version)
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}
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for _, statement := range policy.Statements {
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if err := statement.isValid(); err != nil {
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return err
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}
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}
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for i := range policy.Statements {
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for _, statement := range policy.Statements[i+1:] {
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if policy.Statements[i].Effect != statement.Effect {
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continue
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}
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if !policy.Statements[i].Principal.Equals(statement.Principal) {
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continue
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}
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if !policy.Statements[i].Actions.Equals(statement.Actions) {
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continue
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}
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if !policy.Statements[i].Resources.Equals(statement.Resources) {
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continue
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}
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if policy.Statements[i].Conditions.String() != statement.Conditions.String() {
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continue
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}
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return Errorf("duplicate principal %v, actions %v, resouces %v found in statements %v, %v",
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statement.Principal, statement.Actions,
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statement.Resources, policy.Statements[i],
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statement)
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}
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}
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return nil
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}
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// MarshalJSON - encodes Policy to JSON data.
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func (policy Policy) MarshalJSON() ([]byte, error) {
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if err := policy.isValid(); err != nil {
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return nil, err
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}
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// subtype to avoid recursive call to MarshalJSON()
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type subPolicy Policy
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return json.Marshal(subPolicy(policy))
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}
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// UnmarshalJSON - decodes JSON data to Policy.
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func (policy *Policy) UnmarshalJSON(data []byte) error {
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// subtype to avoid recursive call to UnmarshalJSON()
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type subPolicy Policy
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var sp subPolicy
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if err := json.Unmarshal(data, &sp); err != nil {
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return err
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}
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p := Policy(sp)
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if err := p.isValid(); err != nil {
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return err
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}
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*policy = p
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return nil
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}
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// Validate - validates all statements are for given bucket or not.
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func (policy Policy) Validate(bucketName string) error {
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if err := policy.isValid(); err != nil {
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return err
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}
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for _, statement := range policy.Statements {
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if err := statement.Validate(bucketName); err != nil {
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return err
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}
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}
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return nil
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}
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// ParseConfig - parses data in given reader to Policy.
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func ParseConfig(reader io.Reader, bucketName string) (*Policy, error) {
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var policy Policy
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decoder := json.NewDecoder(reader)
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decoder.DisallowUnknownFields()
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if err := decoder.Decode(&policy); err != nil {
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return nil, Errorf("%w", err)
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}
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err := policy.Validate(bucketName)
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return &policy, err
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}
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