You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
343 lines
10 KiB
343 lines
10 KiB
/*
|
|
* 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 This file implements AWS Access Policy Language parser in
|
|
// accordance with http://docs.aws.amazon.com/AmazonS3/latest/dev/access-policy-language-overview.html
|
|
package cmd
|
|
|
|
import (
|
|
"encoding/json"
|
|
"errors"
|
|
"fmt"
|
|
"io"
|
|
"path"
|
|
"sort"
|
|
"strings"
|
|
)
|
|
|
|
const (
|
|
// AWSResourcePrefix - bucket policy resource prefix.
|
|
AWSResourcePrefix = "arn:aws:s3:::"
|
|
)
|
|
|
|
// supportedActionMap - lists all the actions supported by minio.
|
|
var supportedActionMap = map[string]struct{}{
|
|
"*": {},
|
|
"s3:*": {},
|
|
"s3:GetObject": {},
|
|
"s3:ListBucket": {},
|
|
"s3:PutObject": {},
|
|
"s3:GetBucketLocation": {},
|
|
"s3:DeleteObject": {},
|
|
"s3:AbortMultipartUpload": {},
|
|
"s3:ListBucketMultipartUploads": {},
|
|
"s3:ListMultipartUploadParts": {},
|
|
}
|
|
|
|
// supported Conditions type.
|
|
var supportedConditionsType = map[string]struct{}{
|
|
"StringEquals": {},
|
|
"StringNotEquals": {},
|
|
}
|
|
|
|
// Validate s3:prefix, s3:max-keys are present if not
|
|
// supported keys for the conditions.
|
|
var supportedConditionsKey = map[string]struct{}{
|
|
"s3:prefix": {},
|
|
"s3:max-keys": {},
|
|
}
|
|
|
|
// User - canonical users list.
|
|
type policyUser struct {
|
|
AWS []string
|
|
}
|
|
|
|
// Statement - minio policy statement
|
|
type policyStatement struct {
|
|
Sid string
|
|
Effect string
|
|
Principal policyUser `json:"Principal"`
|
|
Actions []string `json:"Action"`
|
|
Resources []string `json:"Resource"`
|
|
Conditions map[string]map[string]string `json:"Condition,omitempty"`
|
|
}
|
|
|
|
// bucketPolicy - collection of various bucket policy statements.
|
|
type bucketPolicy struct {
|
|
Version string // date in 0000-00-00 format
|
|
Statements []policyStatement `json:"Statement"`
|
|
}
|
|
|
|
// Stringer implementation for the bucket policies.
|
|
func (b bucketPolicy) String() string {
|
|
bbytes, err := json.Marshal(&b)
|
|
if err != nil {
|
|
errorIf(err, "Unable to unmarshal bucket policy into JSON %#v", b)
|
|
return ""
|
|
}
|
|
return string(bbytes)
|
|
}
|
|
|
|
// supportedEffectMap - supported effects.
|
|
var supportedEffectMap = map[string]struct{}{
|
|
"Allow": {},
|
|
"Deny": {},
|
|
}
|
|
|
|
// isValidActions - are actions valid.
|
|
func isValidActions(actions []string) (err error) {
|
|
// Statement actions cannot be empty.
|
|
if len(actions) == 0 {
|
|
err = errors.New("Action list cannot be empty.")
|
|
return err
|
|
}
|
|
for _, action := range actions {
|
|
if _, ok := supportedActionMap[action]; !ok {
|
|
err = errors.New("Unsupported action found: ‘" + action + "’, please validate your policy document.")
|
|
return err
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// isValidEffect - is effect valid.
|
|
func isValidEffect(effect string) error {
|
|
// Statement effect cannot be empty.
|
|
if len(effect) == 0 {
|
|
err := errors.New("Policy effect cannot be empty.")
|
|
return err
|
|
}
|
|
_, ok := supportedEffectMap[effect]
|
|
if !ok {
|
|
err := errors.New("Unsupported Effect found: ‘" + effect + "’, please validate your policy document.")
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// isValidResources - are valid resources.
|
|
func isValidResources(resources []string) (err error) {
|
|
// Statement resources cannot be empty.
|
|
if len(resources) == 0 {
|
|
err = errors.New("Resource list cannot be empty.")
|
|
return err
|
|
}
|
|
for _, resource := range resources {
|
|
if !strings.HasPrefix(resource, AWSResourcePrefix) {
|
|
err = errors.New("Unsupported resource style found: ‘" + resource + "’, please validate your policy document.")
|
|
return err
|
|
}
|
|
resourceSuffix := strings.SplitAfter(resource, AWSResourcePrefix)[1]
|
|
if len(resourceSuffix) == 0 || strings.HasPrefix(resourceSuffix, "/") {
|
|
err = errors.New("Invalid resource style found: ‘" + resource + "’, please validate your policy document.")
|
|
return err
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// isValidPrincipals - are valid principals.
|
|
func isValidPrincipals(principals []string) (err error) {
|
|
// Statement principal should have a value.
|
|
if len(principals) == 0 {
|
|
err = errors.New("Principal cannot be empty.")
|
|
return err
|
|
}
|
|
for _, principal := range principals {
|
|
// Minio does not support or implement IAM, "*" is the only valid value.
|
|
// Amazon s3 doc on principals: http://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements.html#Principal
|
|
if principal != "*" {
|
|
err = fmt.Errorf("Unsupported principal style found: ‘%s’, please validate your policy document.", principal)
|
|
return err
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// isValidConditions - are valid conditions.
|
|
func isValidConditions(conditions map[string]map[string]string) (err error) {
|
|
// Returns true if string 'a' is found in the list.
|
|
findString := func(a string, list []string) bool {
|
|
for _, b := range list {
|
|
if b == a {
|
|
return true
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
conditionKeyVal := make(map[string][]string)
|
|
// Verify conditions should be valid.
|
|
// Validate if stringEquals, stringNotEquals are present
|
|
// if not throw an error.
|
|
for conditionType := range conditions {
|
|
_, validType := supportedConditionsType[conditionType]
|
|
if !validType {
|
|
err = fmt.Errorf("Unsupported condition type '%s', please validate your policy document.", conditionType)
|
|
return err
|
|
}
|
|
for key := range conditions[conditionType] {
|
|
_, validKey := supportedConditionsKey[key]
|
|
if !validKey {
|
|
err = fmt.Errorf("Unsupported condition key '%s', please validate your policy document.", conditionType)
|
|
return err
|
|
}
|
|
conditionArray, ok := conditionKeyVal[key]
|
|
if ok && findString(conditions[conditionType][key], conditionArray) {
|
|
err = fmt.Errorf("Ambigious condition values for key '%s', please validate your policy document.", key)
|
|
return err
|
|
}
|
|
conditionKeyVal[key] = append(conditionKeyVal[key], conditions[conditionType][key])
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// List of actions for which prefixes are not allowed.
|
|
var invalidPrefixActions = map[string]struct{}{
|
|
"s3:GetBucketLocation": {},
|
|
"s3:ListBucket": {},
|
|
"s3:ListBucketMultipartUploads": {},
|
|
// Add actions which do not honor prefixes.
|
|
}
|
|
|
|
// resourcePrefix - provides the prefix removing any wildcards.
|
|
func resourcePrefix(resource string) string {
|
|
if strings.HasSuffix(resource, "*") {
|
|
resource = strings.TrimSuffix(resource, "*")
|
|
}
|
|
return path.Clean(resource)
|
|
}
|
|
|
|
// checkBucketPolicyResources validates Resources in unmarshalled bucket policy structure.
|
|
// First valation of Resources done for given set of Actions.
|
|
// Later its validated for recursive Resources.
|
|
func checkBucketPolicyResources(bucket string, bucketPolicy *bucketPolicy) APIErrorCode {
|
|
// Validate statements for special actions and collect resources
|
|
// for others to validate nesting.
|
|
var resourceMap = make(map[string]struct{})
|
|
for _, statement := range bucketPolicy.Statements {
|
|
for _, action := range statement.Actions {
|
|
for _, resource := range statement.Resources {
|
|
resourcePrefix := strings.SplitAfter(resource, AWSResourcePrefix)[1]
|
|
if _, ok := invalidPrefixActions[action]; ok {
|
|
// Resource prefix is not equal to bucket for
|
|
// prefix invalid actions, reject them.
|
|
if resourcePrefix != bucket {
|
|
return ErrMalformedPolicy
|
|
}
|
|
} else {
|
|
// For all other actions validate if resourcePrefix begins
|
|
// with bucket name, if not reject them.
|
|
if strings.Split(resourcePrefix, "/")[0] != bucket {
|
|
return ErrMalformedPolicy
|
|
}
|
|
// All valid resources collect them separately to verify nesting.
|
|
resourceMap[resourcePrefix] = struct{}{}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
var resources []string
|
|
for resource := range resourceMap {
|
|
resources = append(resources, resourcePrefix(resource))
|
|
}
|
|
|
|
// Sort strings as shorter first.
|
|
sort.Strings(resources)
|
|
|
|
for len(resources) > 1 {
|
|
var resource string
|
|
resource, resources = resources[0], resources[1:]
|
|
// Loop through all resources, if one of them matches with
|
|
// previous shorter one, it means we have detected
|
|
// nesting. Reject such rules.
|
|
for _, otherResource := range resources {
|
|
// Common prefix reject such rules.
|
|
if strings.HasPrefix(otherResource, resource) {
|
|
return ErrPolicyNesting
|
|
}
|
|
}
|
|
}
|
|
|
|
// No errors found.
|
|
return ErrNone
|
|
}
|
|
|
|
// parseBucketPolicy - parses and validates if bucket policy is of
|
|
// proper JSON and follows allowed restrictions with policy standards.
|
|
func parseBucketPolicy(bucketPolicyReader io.Reader, policy *bucketPolicy) (err error) {
|
|
// Parse bucket policy reader.
|
|
decoder := json.NewDecoder(bucketPolicyReader)
|
|
if err = decoder.Decode(&policy); err != nil {
|
|
return err
|
|
}
|
|
|
|
// Policy version cannot be empty.
|
|
if len(policy.Version) == 0 {
|
|
err = errors.New("Policy version cannot be empty.")
|
|
return err
|
|
}
|
|
|
|
// Policy statements cannot be empty.
|
|
if len(policy.Statements) == 0 {
|
|
err = errors.New("Policy statement cannot be empty.")
|
|
return err
|
|
}
|
|
|
|
// Loop through all policy statements and validate entries.
|
|
for _, statement := range policy.Statements {
|
|
// Statement effect should be valid.
|
|
if err := isValidEffect(statement.Effect); err != nil {
|
|
return err
|
|
}
|
|
// Statement principal should be supported format.
|
|
if err := isValidPrincipals(statement.Principal.AWS); err != nil {
|
|
return err
|
|
}
|
|
// Statement actions should be valid.
|
|
if err := isValidActions(statement.Actions); err != nil {
|
|
return err
|
|
}
|
|
// Statement resources should be valid.
|
|
if err := isValidResources(statement.Resources); err != nil {
|
|
return err
|
|
}
|
|
// Statement conditions should be valid.
|
|
if err := isValidConditions(statement.Conditions); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
|
|
// Separate deny and allow statements, so that we can apply deny
|
|
// statements in the beginning followed by Allow statements.
|
|
var denyStatements []policyStatement
|
|
var allowStatements []policyStatement
|
|
for _, statement := range policy.Statements {
|
|
if statement.Effect == "Deny" {
|
|
denyStatements = append(denyStatements, statement)
|
|
continue
|
|
}
|
|
// else if statement.Effect == "Allow"
|
|
allowStatements = append(allowStatements, statement)
|
|
}
|
|
|
|
// Deny statements are enforced first once matched.
|
|
policy.Statements = append(denyStatements, allowStatements...)
|
|
|
|
// Return successfully parsed policy structure.
|
|
return nil
|
|
}
|
|
|