minio/cmd/bucket-policy.go

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/*
* Minio Cloud Storage, (C) 2015, 2016 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 cmd
import (
"bytes"
"encoding/json"
"io"
"sync"
)
const (
// Static prefix to be used while constructing bucket ARN.
// refer to S3 docs for more info.
bucketARNPrefix = "arn:" + eventSource + ":::"
// Bucket policy config name.
bucketPolicyConfig = "policy.json"
)
// Variable represents bucket policies in memory.
var globalBucketPolicies *bucketPolicies
// Global bucket policies list, policies are enforced on each bucket looking
// through the policies here.
type bucketPolicies struct {
rwMutex *sync.RWMutex
// Collection of 'bucket' policies.
bucketPolicyConfigs map[string]*bucketPolicy
}
// Represent a policy change
type policyChange struct {
// isRemove is true if the policy change is to delete the
// policy on a bucket.
IsRemove bool
// represents the new policy for the bucket
BktPolicy *bucketPolicy
}
// Fetch bucket policy for a given bucket.
func (bp bucketPolicies) GetBucketPolicy(bucket string) *bucketPolicy {
bp.rwMutex.RLock()
defer bp.rwMutex.RUnlock()
return bp.bucketPolicyConfigs[bucket]
}
// Set a new bucket policy for a bucket, this operation will overwrite
// any previous bucket policies for the bucket.
func (bp *bucketPolicies) SetBucketPolicy(bucket string, pCh policyChange) error {
bp.rwMutex.Lock()
defer bp.rwMutex.Unlock()
if pCh.IsRemove {
delete(bp.bucketPolicyConfigs, bucket)
} else {
if pCh.BktPolicy == nil {
return errInvalidArgument
}
bp.bucketPolicyConfigs[bucket] = pCh.BktPolicy
}
return nil
}
// Loads all bucket policies from persistent layer.
func loadAllBucketPolicies(objAPI ObjectLayer) (policies map[string]*bucketPolicy, err error) {
// List buckets to proceed loading all notification configuration.
buckets, err := objAPI.ListBuckets()
errorIf(err, "Unable to list buckets.")
if err != nil {
return nil, errorCause(err)
}
policies = make(map[string]*bucketPolicy)
var pErrs []error
// Loads bucket policy.
for _, bucket := range buckets {
policy, pErr := readBucketPolicy(bucket.Name, objAPI)
if pErr != nil {
// net.Dial fails for rpc client or any
// other unexpected errors during net.Dial.
if !isErrIgnored(pErr, errDiskNotFound) {
if !isErrBucketPolicyNotFound(pErr) {
pErrs = append(pErrs, pErr)
}
}
// Continue to load other bucket policies if possible.
continue
}
policies[bucket.Name] = policy
}
// Look for any errors occurred while reading bucket policies.
for _, pErr := range pErrs {
if pErr != nil {
return policies, pErr
}
}
// Success.
return policies, nil
}
// Intialize all bucket policies.
func initBucketPolicies(objAPI ObjectLayer) error {
if objAPI == nil {
return errInvalidArgument
}
// Read all bucket policies.
policies, err := loadAllBucketPolicies(objAPI)
if err != nil {
return err
}
// Populate global bucket collection.
globalBucketPolicies = &bucketPolicies{
rwMutex: &sync.RWMutex{},
bucketPolicyConfigs: policies,
}
// Success.
return nil
}
// readBucketPolicyJSON - reads bucket policy for an input bucket, returns BucketPolicyNotFound
// if bucket policy is not found.
func readBucketPolicyJSON(bucket string, objAPI ObjectLayer) (bucketPolicyReader io.Reader, err error) {
policyPath := pathJoin(bucketConfigPrefix, bucket, bucketPolicyConfig)
// Acquire a read lock on policy config before reading.
objLock := globalNSMutex.NewNSLock(minioMetaBucket, policyPath)
if err = objLock.GetRLock(globalOperationTimeout); err != nil {
return nil, err
}
defer objLock.RUnlock()
var buffer bytes.Buffer
err = objAPI.GetObject(minioMetaBucket, policyPath, 0, -1, &buffer)
if err != nil {
if isErrObjectNotFound(err) || isErrIncompleteBody(err) {
return nil, BucketPolicyNotFound{Bucket: bucket}
}
errorIf(err, "Unable to load policy for the bucket %s.", bucket)
return nil, errorCause(err)
}
return &buffer, nil
}
// readBucketPolicy - reads bucket policy for an input bucket, returns BucketPolicyNotFound
// if bucket policy is not found. This function also parses the bucket policy into an object.
func readBucketPolicy(bucket string, objAPI ObjectLayer) (*bucketPolicy, error) {
// Read bucket policy JSON.
bucketPolicyReader, err := readBucketPolicyJSON(bucket, objAPI)
if err != nil {
return nil, err
}
// Parse the saved policy.
var policy = &bucketPolicy{}
err = parseBucketPolicy(bucketPolicyReader, policy)
if err != nil {
return nil, err
}
return policy, nil
}
// removeBucketPolicy - removes any previously written bucket policy. Returns BucketPolicyNotFound
// if no policies are found.
func removeBucketPolicy(bucket string, objAPI ObjectLayer) error {
policyPath := pathJoin(bucketConfigPrefix, bucket, bucketPolicyConfig)
// Acquire a write lock on policy config before modifying.
objLock := globalNSMutex.NewNSLock(minioMetaBucket, policyPath)
if err := objLock.GetLock(globalOperationTimeout); err != nil {
return err
}
defer objLock.Unlock()
if err := objAPI.DeleteObject(minioMetaBucket, policyPath); err != nil {
errorIf(err, "Unable to remove bucket-policy on bucket %s.", bucket)
err = errorCause(err)
if _, ok := err.(ObjectNotFound); ok {
return BucketPolicyNotFound{Bucket: bucket}
}
return err
}
return nil
}
// writeBucketPolicy - save a bucket policy that is assumed to be validated.
func writeBucketPolicy(bucket string, objAPI ObjectLayer, bpy *bucketPolicy) error {
buf, err := json.Marshal(bpy)
if err != nil {
errorIf(err, "Unable to marshal bucket policy '%v' to JSON", *bpy)
return err
}
policyPath := pathJoin(bucketConfigPrefix, bucket, bucketPolicyConfig)
// Acquire a write lock on policy config before modifying.
objLock := globalNSMutex.NewNSLock(minioMetaBucket, policyPath)
if err := objLock.GetLock(globalOperationTimeout); err != nil {
return err
}
defer objLock.Unlock()
if _, err := objAPI.PutObject(minioMetaBucket, policyPath, int64(len(buf)), bytes.NewReader(buf), nil, ""); err != nil {
errorIf(err, "Unable to set policy for the bucket %s", bucket)
return errorCause(err)
}
return nil
}
func parseAndPersistBucketPolicy(bucket string, policyBytes []byte, objAPI ObjectLayer) APIErrorCode {
// Parse bucket policy.
var policy = &bucketPolicy{}
err := parseBucketPolicy(bytes.NewReader(policyBytes), policy)
if err != nil {
errorIf(err, "Unable to parse bucket policy.")
return ErrInvalidPolicyDocument
}
// Parse check bucket policy.
if s3Error := checkBucketPolicyResources(bucket, policy); s3Error != ErrNone {
return s3Error
}
// Acquire a write lock on bucket before modifying its configuration.
bucketLock := globalNSMutex.NewNSLock(bucket, "")
if bucketLock.GetLock(globalOperationTimeout) != nil {
return ErrOperationTimedOut
}
// Release lock after notifying peers
defer bucketLock.Unlock()
// Save bucket policy.
if err = persistAndNotifyBucketPolicyChange(bucket, policyChange{false, policy}, objAPI); err != nil {
switch err.(type) {
case BucketNameInvalid:
return ErrInvalidBucketName
case BucketNotFound:
return ErrNoSuchBucket
default:
errorIf(err, "Unable to save bucket policy.")
return ErrInternalError
}
}
return ErrNone
}
// persistAndNotifyBucketPolicyChange - takes a policyChange argument,
// persists it to storage, and notify nodes in the cluster about the
// change. In-memory state is updated in response to the notification.
func persistAndNotifyBucketPolicyChange(bucket string, pCh policyChange, objAPI ObjectLayer) error {
if pCh.IsRemove {
if err := removeBucketPolicy(bucket, objAPI); err != nil {
return err
}
} else {
if pCh.BktPolicy == nil {
return errInvalidArgument
}
if err := writeBucketPolicy(bucket, objAPI, pCh.BktPolicy); err != nil {
return err
}
}
// Notify all peers (including self) to update in-memory state
S3PeersUpdateBucketPolicy(bucket, pCh)
return nil
}