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restic/vendor/github.com/minio/minio-go/pkg/policy/bucket-policy.go
2017-07-23 14:25:38 +02:00

635 lines
19 KiB
Go

/*
* Minio Go Library for Amazon S3 Compatible Cloud Storage (C) 2015 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 (
"reflect"
"strings"
"github.com/minio/minio-go/pkg/set"
)
// BucketPolicy - Bucket level policy.
type BucketPolicy string
// Different types of Policies currently supported for buckets.
const (
BucketPolicyNone BucketPolicy = "none"
BucketPolicyReadOnly = "readonly"
BucketPolicyReadWrite = "readwrite"
BucketPolicyWriteOnly = "writeonly"
)
// IsValidBucketPolicy - returns true if policy is valid and supported, false otherwise.
func (p BucketPolicy) IsValidBucketPolicy() bool {
switch p {
case BucketPolicyNone, BucketPolicyReadOnly, BucketPolicyReadWrite, BucketPolicyWriteOnly:
return true
}
return false
}
// Resource prefix for all aws resources.
const awsResourcePrefix = "arn:aws:s3:::"
// Common bucket actions for both read and write policies.
var commonBucketActions = set.CreateStringSet("s3:GetBucketLocation")
// Read only bucket actions.
var readOnlyBucketActions = set.CreateStringSet("s3:ListBucket")
// Write only bucket actions.
var writeOnlyBucketActions = set.CreateStringSet("s3:ListBucketMultipartUploads")
// Read only object actions.
var readOnlyObjectActions = set.CreateStringSet("s3:GetObject")
// Write only object actions.
var writeOnlyObjectActions = set.CreateStringSet("s3:AbortMultipartUpload", "s3:DeleteObject", "s3:ListMultipartUploadParts", "s3:PutObject")
// Read and write object actions.
var readWriteObjectActions = readOnlyObjectActions.Union(writeOnlyObjectActions)
// All valid bucket and object actions.
var validActions = commonBucketActions.
Union(readOnlyBucketActions).
Union(writeOnlyBucketActions).
Union(readOnlyObjectActions).
Union(writeOnlyObjectActions)
var startsWithFunc = func(resource string, resourcePrefix string) bool {
return strings.HasPrefix(resource, resourcePrefix)
}
// User - canonical users list.
type User struct {
AWS set.StringSet `json:"AWS,omitempty"`
CanonicalUser set.StringSet `json:"CanonicalUser,omitempty"`
}
// Statement - minio policy statement
type Statement struct {
Actions set.StringSet `json:"Action"`
Conditions ConditionMap `json:"Condition,omitempty"`
Effect string
Principal User `json:"Principal"`
Resources set.StringSet `json:"Resource"`
Sid string
}
// BucketAccessPolicy - minio policy collection
type BucketAccessPolicy struct {
Version string // date in YYYY-MM-DD format
Statements []Statement `json:"Statement"`
}
// isValidStatement - returns whether given statement is valid to process for given bucket name.
func isValidStatement(statement Statement, bucketName string) bool {
if statement.Actions.Intersection(validActions).IsEmpty() {
return false
}
if statement.Effect != "Allow" {
return false
}
if statement.Principal.AWS == nil || !statement.Principal.AWS.Contains("*") {
return false
}
bucketResource := awsResourcePrefix + bucketName
if statement.Resources.Contains(bucketResource) {
return true
}
if statement.Resources.FuncMatch(startsWithFunc, bucketResource+"/").IsEmpty() {
return false
}
return true
}
// Returns new statements with bucket actions for given policy.
func newBucketStatement(policy BucketPolicy, bucketName string, prefix string) (statements []Statement) {
statements = []Statement{}
if policy == BucketPolicyNone || bucketName == "" {
return statements
}
bucketResource := set.CreateStringSet(awsResourcePrefix + bucketName)
statement := Statement{
Actions: commonBucketActions,
Effect: "Allow",
Principal: User{AWS: set.CreateStringSet("*")},
Resources: bucketResource,
Sid: "",
}
statements = append(statements, statement)
if policy == BucketPolicyReadOnly || policy == BucketPolicyReadWrite {
statement = Statement{
Actions: readOnlyBucketActions,
Effect: "Allow",
Principal: User{AWS: set.CreateStringSet("*")},
Resources: bucketResource,
Sid: "",
}
if prefix != "" {
condKeyMap := make(ConditionKeyMap)
condKeyMap.Add("s3:prefix", set.CreateStringSet(prefix))
condMap := make(ConditionMap)
condMap.Add("StringEquals", condKeyMap)
statement.Conditions = condMap
}
statements = append(statements, statement)
}
if policy == BucketPolicyWriteOnly || policy == BucketPolicyReadWrite {
statement = Statement{
Actions: writeOnlyBucketActions,
Effect: "Allow",
Principal: User{AWS: set.CreateStringSet("*")},
Resources: bucketResource,
Sid: "",
}
statements = append(statements, statement)
}
return statements
}
// Returns new statements contains object actions for given policy.
func newObjectStatement(policy BucketPolicy, bucketName string, prefix string) (statements []Statement) {
statements = []Statement{}
if policy == BucketPolicyNone || bucketName == "" {
return statements
}
statement := Statement{
Effect: "Allow",
Principal: User{AWS: set.CreateStringSet("*")},
Resources: set.CreateStringSet(awsResourcePrefix + bucketName + "/" + prefix + "*"),
Sid: "",
}
if policy == BucketPolicyReadOnly {
statement.Actions = readOnlyObjectActions
} else if policy == BucketPolicyWriteOnly {
statement.Actions = writeOnlyObjectActions
} else if policy == BucketPolicyReadWrite {
statement.Actions = readWriteObjectActions
}
statements = append(statements, statement)
return statements
}
// Returns new statements for given policy, bucket and prefix.
func newStatements(policy BucketPolicy, bucketName string, prefix string) (statements []Statement) {
statements = []Statement{}
ns := newBucketStatement(policy, bucketName, prefix)
statements = append(statements, ns...)
ns = newObjectStatement(policy, bucketName, prefix)
statements = append(statements, ns...)
return statements
}
// Returns whether given bucket statements are used by other than given prefix statements.
func getInUsePolicy(statements []Statement, bucketName string, prefix string) (readOnlyInUse, writeOnlyInUse bool) {
resourcePrefix := awsResourcePrefix + bucketName + "/"
objectResource := awsResourcePrefix + bucketName + "/" + prefix + "*"
for _, s := range statements {
if !s.Resources.Contains(objectResource) && !s.Resources.FuncMatch(startsWithFunc, resourcePrefix).IsEmpty() {
if s.Actions.Intersection(readOnlyObjectActions).Equals(readOnlyObjectActions) {
readOnlyInUse = true
}
if s.Actions.Intersection(writeOnlyObjectActions).Equals(writeOnlyObjectActions) {
writeOnlyInUse = true
}
}
if readOnlyInUse && writeOnlyInUse {
break
}
}
return readOnlyInUse, writeOnlyInUse
}
// Removes object actions in given statement.
func removeObjectActions(statement Statement, objectResource string) Statement {
if statement.Conditions == nil {
if len(statement.Resources) > 1 {
statement.Resources.Remove(objectResource)
} else {
statement.Actions = statement.Actions.Difference(readOnlyObjectActions)
statement.Actions = statement.Actions.Difference(writeOnlyObjectActions)
}
}
return statement
}
// Removes bucket actions for given policy in given statement.
func removeBucketActions(statement Statement, prefix string, bucketResource string, readOnlyInUse, writeOnlyInUse bool) Statement {
removeReadOnly := func() {
if !statement.Actions.Intersection(readOnlyBucketActions).Equals(readOnlyBucketActions) {
return
}
if statement.Conditions == nil {
statement.Actions = statement.Actions.Difference(readOnlyBucketActions)
return
}
if prefix != "" {
stringEqualsValue := statement.Conditions["StringEquals"]
values := set.NewStringSet()
if stringEqualsValue != nil {
values = stringEqualsValue["s3:prefix"]
if values == nil {
values = set.NewStringSet()
}
}
values.Remove(prefix)
if stringEqualsValue != nil {
if values.IsEmpty() {
delete(stringEqualsValue, "s3:prefix")
}
if len(stringEqualsValue) == 0 {
delete(statement.Conditions, "StringEquals")
}
}
if len(statement.Conditions) == 0 {
statement.Conditions = nil
statement.Actions = statement.Actions.Difference(readOnlyBucketActions)
}
}
}
removeWriteOnly := func() {
if statement.Conditions == nil {
statement.Actions = statement.Actions.Difference(writeOnlyBucketActions)
}
}
if len(statement.Resources) > 1 {
statement.Resources.Remove(bucketResource)
} else {
if !readOnlyInUse {
removeReadOnly()
}
if !writeOnlyInUse {
removeWriteOnly()
}
}
return statement
}
// Returns statements containing removed actions/statements for given
// policy, bucket name and prefix.
func removeStatements(statements []Statement, bucketName string, prefix string) []Statement {
bucketResource := awsResourcePrefix + bucketName
objectResource := awsResourcePrefix + bucketName + "/" + prefix + "*"
readOnlyInUse, writeOnlyInUse := getInUsePolicy(statements, bucketName, prefix)
out := []Statement{}
readOnlyBucketStatements := []Statement{}
s3PrefixValues := set.NewStringSet()
for _, statement := range statements {
if !isValidStatement(statement, bucketName) {
out = append(out, statement)
continue
}
if statement.Resources.Contains(bucketResource) {
if statement.Conditions != nil {
statement = removeBucketActions(statement, prefix, bucketResource, false, false)
} else {
statement = removeBucketActions(statement, prefix, bucketResource, readOnlyInUse, writeOnlyInUse)
}
} else if statement.Resources.Contains(objectResource) {
statement = removeObjectActions(statement, objectResource)
}
if !statement.Actions.IsEmpty() {
if statement.Resources.Contains(bucketResource) &&
statement.Actions.Intersection(readOnlyBucketActions).Equals(readOnlyBucketActions) &&
statement.Effect == "Allow" &&
statement.Principal.AWS.Contains("*") {
if statement.Conditions != nil {
stringEqualsValue := statement.Conditions["StringEquals"]
values := set.NewStringSet()
if stringEqualsValue != nil {
values = stringEqualsValue["s3:prefix"]
if values == nil {
values = set.NewStringSet()
}
}
s3PrefixValues = s3PrefixValues.Union(values.ApplyFunc(func(v string) string {
return bucketResource + "/" + v + "*"
}))
} else if !s3PrefixValues.IsEmpty() {
readOnlyBucketStatements = append(readOnlyBucketStatements, statement)
continue
}
}
out = append(out, statement)
}
}
skipBucketStatement := true
resourcePrefix := awsResourcePrefix + bucketName + "/"
for _, statement := range out {
if !statement.Resources.FuncMatch(startsWithFunc, resourcePrefix).IsEmpty() &&
s3PrefixValues.Intersection(statement.Resources).IsEmpty() {
skipBucketStatement = false
break
}
}
for _, statement := range readOnlyBucketStatements {
if skipBucketStatement &&
statement.Resources.Contains(bucketResource) &&
statement.Effect == "Allow" &&
statement.Principal.AWS.Contains("*") &&
statement.Conditions == nil {
continue
}
out = append(out, statement)
}
if len(out) == 1 {
statement := out[0]
if statement.Resources.Contains(bucketResource) &&
statement.Actions.Intersection(commonBucketActions).Equals(commonBucketActions) &&
statement.Effect == "Allow" &&
statement.Principal.AWS.Contains("*") &&
statement.Conditions == nil {
out = []Statement{}
}
}
return out
}
// Appends given statement into statement list to have unique statements.
// - If statement already exists in statement list, it ignores.
// - If statement exists with different conditions, they are merged.
// - Else the statement is appended to statement list.
func appendStatement(statements []Statement, statement Statement) []Statement {
for i, s := range statements {
if s.Actions.Equals(statement.Actions) &&
s.Effect == statement.Effect &&
s.Principal.AWS.Equals(statement.Principal.AWS) &&
reflect.DeepEqual(s.Conditions, statement.Conditions) {
statements[i].Resources = s.Resources.Union(statement.Resources)
return statements
} else if s.Resources.Equals(statement.Resources) &&
s.Effect == statement.Effect &&
s.Principal.AWS.Equals(statement.Principal.AWS) &&
reflect.DeepEqual(s.Conditions, statement.Conditions) {
statements[i].Actions = s.Actions.Union(statement.Actions)
return statements
}
if s.Resources.Intersection(statement.Resources).Equals(statement.Resources) &&
s.Actions.Intersection(statement.Actions).Equals(statement.Actions) &&
s.Effect == statement.Effect &&
s.Principal.AWS.Intersection(statement.Principal.AWS).Equals(statement.Principal.AWS) {
if reflect.DeepEqual(s.Conditions, statement.Conditions) {
return statements
}
if s.Conditions != nil && statement.Conditions != nil {
if s.Resources.Equals(statement.Resources) {
statements[i].Conditions = mergeConditionMap(s.Conditions, statement.Conditions)
return statements
}
}
}
}
if !(statement.Actions.IsEmpty() && statement.Resources.IsEmpty()) {
return append(statements, statement)
}
return statements
}
// Appends two statement lists.
func appendStatements(statements []Statement, appendStatements []Statement) []Statement {
for _, s := range appendStatements {
statements = appendStatement(statements, s)
}
return statements
}
// Returns policy of given bucket statement.
func getBucketPolicy(statement Statement, prefix string) (commonFound, readOnly, writeOnly bool) {
if !(statement.Effect == "Allow" && statement.Principal.AWS.Contains("*")) {
return commonFound, readOnly, writeOnly
}
if statement.Actions.Intersection(commonBucketActions).Equals(commonBucketActions) &&
statement.Conditions == nil {
commonFound = true
}
if statement.Actions.Intersection(writeOnlyBucketActions).Equals(writeOnlyBucketActions) &&
statement.Conditions == nil {
writeOnly = true
}
if statement.Actions.Intersection(readOnlyBucketActions).Equals(readOnlyBucketActions) {
if prefix != "" && statement.Conditions != nil {
if stringEqualsValue, ok := statement.Conditions["StringEquals"]; ok {
if s3PrefixValues, ok := stringEqualsValue["s3:prefix"]; ok {
if s3PrefixValues.Contains(prefix) {
readOnly = true
}
}
} else if stringNotEqualsValue, ok := statement.Conditions["StringNotEquals"]; ok {
if s3PrefixValues, ok := stringNotEqualsValue["s3:prefix"]; ok {
if !s3PrefixValues.Contains(prefix) {
readOnly = true
}
}
}
} else if prefix == "" && statement.Conditions == nil {
readOnly = true
} else if prefix != "" && statement.Conditions == nil {
readOnly = true
}
}
return commonFound, readOnly, writeOnly
}
// Returns policy of given object statement.
func getObjectPolicy(statement Statement) (readOnly bool, writeOnly bool) {
if statement.Effect == "Allow" &&
statement.Principal.AWS.Contains("*") &&
statement.Conditions == nil {
if statement.Actions.Intersection(readOnlyObjectActions).Equals(readOnlyObjectActions) {
readOnly = true
}
if statement.Actions.Intersection(writeOnlyObjectActions).Equals(writeOnlyObjectActions) {
writeOnly = true
}
}
return readOnly, writeOnly
}
// GetPolicy - Returns policy of given bucket name, prefix in given statements.
func GetPolicy(statements []Statement, bucketName string, prefix string) BucketPolicy {
bucketResource := awsResourcePrefix + bucketName
objectResource := awsResourcePrefix + bucketName + "/" + prefix + "*"
bucketCommonFound := false
bucketReadOnly := false
bucketWriteOnly := false
matchedResource := ""
objReadOnly := false
objWriteOnly := false
for _, s := range statements {
matchedObjResources := set.NewStringSet()
if s.Resources.Contains(objectResource) {
matchedObjResources.Add(objectResource)
} else {
matchedObjResources = s.Resources.FuncMatch(resourceMatch, objectResource)
}
if !matchedObjResources.IsEmpty() {
readOnly, writeOnly := getObjectPolicy(s)
for resource := range matchedObjResources {
if len(matchedResource) < len(resource) {
objReadOnly = readOnly
objWriteOnly = writeOnly
matchedResource = resource
} else if len(matchedResource) == len(resource) {
objReadOnly = objReadOnly || readOnly
objWriteOnly = objWriteOnly || writeOnly
matchedResource = resource
}
}
} else if s.Resources.Contains(bucketResource) {
commonFound, readOnly, writeOnly := getBucketPolicy(s, prefix)
bucketCommonFound = bucketCommonFound || commonFound
bucketReadOnly = bucketReadOnly || readOnly
bucketWriteOnly = bucketWriteOnly || writeOnly
}
}
policy := BucketPolicyNone
if bucketCommonFound {
if bucketReadOnly && bucketWriteOnly && objReadOnly && objWriteOnly {
policy = BucketPolicyReadWrite
} else if bucketReadOnly && objReadOnly {
policy = BucketPolicyReadOnly
} else if bucketWriteOnly && objWriteOnly {
policy = BucketPolicyWriteOnly
}
}
return policy
}
// GetPolicies - returns a map of policies rules of given bucket name, prefix in given statements.
func GetPolicies(statements []Statement, bucketName string) map[string]BucketPolicy {
policyRules := map[string]BucketPolicy{}
objResources := set.NewStringSet()
// Search all resources related to objects policy
for _, s := range statements {
for r := range s.Resources {
if strings.HasPrefix(r, awsResourcePrefix+bucketName+"/") {
objResources.Add(r)
}
}
}
// Pretend that policy resource as an actual object and fetch its policy
for r := range objResources {
// Put trailing * if exists in asterisk
asterisk := ""
if strings.HasSuffix(r, "*") {
r = r[:len(r)-1]
asterisk = "*"
}
objectPath := r[len(awsResourcePrefix+bucketName)+1:]
p := GetPolicy(statements, bucketName, objectPath)
policyRules[bucketName+"/"+objectPath+asterisk] = p
}
return policyRules
}
// SetPolicy - Returns new statements containing policy of given bucket name and prefix are appended.
func SetPolicy(statements []Statement, policy BucketPolicy, bucketName string, prefix string) []Statement {
out := removeStatements(statements, bucketName, prefix)
// fmt.Println("out = ")
// printstatement(out)
ns := newStatements(policy, bucketName, prefix)
// fmt.Println("ns = ")
// printstatement(ns)
rv := appendStatements(out, ns)
// fmt.Println("rv = ")
// printstatement(rv)
return rv
}
// Match function matches wild cards in 'pattern' for resource.
func resourceMatch(pattern, resource string) bool {
if pattern == "" {
return resource == pattern
}
if pattern == "*" {
return true
}
parts := strings.Split(pattern, "*")
if len(parts) == 1 {
return resource == pattern
}
tGlob := strings.HasSuffix(pattern, "*")
end := len(parts) - 1
if !strings.HasPrefix(resource, parts[0]) {
return false
}
for i := 1; i < end; i++ {
if !strings.Contains(resource, parts[i]) {
return false
}
idx := strings.Index(resource, parts[i]) + len(parts[i])
resource = resource[idx:]
}
return tGlob || strings.HasSuffix(resource, parts[end])
}