This PR fixes a security issue where an IAM user based on his policy is granted more privileges than restricted by the users IAM policy. This is due to an issue of prefix based Matcher() function which was incorrectly matching prefix based on resource prefixes instead of exact match.
138 lines
3.4 KiB
Go
138 lines
3.4 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 iampolicy
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import (
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"encoding/json"
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"fmt"
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"path"
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"strings"
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"github.com/minio/minio/pkg/policy/condition"
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"github.com/minio/minio/pkg/wildcard"
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)
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// ResourceARNPrefix - resource ARN prefix as per AWS S3 specification.
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const ResourceARNPrefix = "arn:aws:s3:::"
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// Resource - resource in policy statement.
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type Resource struct {
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BucketName string
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Pattern string
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}
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func (r Resource) isBucketPattern() bool {
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return !strings.Contains(r.Pattern, "/") || r.Pattern == "*"
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}
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func (r Resource) isObjectPattern() bool {
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return strings.Contains(r.Pattern, "/") || strings.Contains(r.BucketName, "*") || r.Pattern == "*/*"
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}
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// IsValid - checks whether Resource is valid or not.
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func (r Resource) IsValid() bool {
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return r.Pattern != ""
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}
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// Match - matches object name with resource pattern.
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func (r Resource) Match(resource string, conditionValues map[string][]string) bool {
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pattern := r.Pattern
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for _, key := range condition.CommonKeys {
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// Empty values are not supported for policy variables.
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if rvalues, ok := conditionValues[key.Name()]; ok && rvalues[0] != "" {
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pattern = strings.Replace(pattern, key.VarName(), rvalues[0], -1)
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}
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}
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if path.Clean(resource) == pattern {
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return true
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}
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return wildcard.Match(pattern, resource)
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}
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// MarshalJSON - encodes Resource to JSON data.
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func (r Resource) MarshalJSON() ([]byte, error) {
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if !r.IsValid() {
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return nil, fmt.Errorf("invalid resource %v", r)
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}
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return json.Marshal(r.String())
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}
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func (r Resource) String() string {
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return ResourceARNPrefix + r.Pattern
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}
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// UnmarshalJSON - decodes JSON data to Resource.
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func (r *Resource) UnmarshalJSON(data []byte) error {
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var s string
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if err := json.Unmarshal(data, &s); err != nil {
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return err
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}
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parsedResource, err := parseResource(s)
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if err != nil {
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return err
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}
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*r = parsedResource
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return nil
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}
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// Validate - validates Resource is for given bucket or not.
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func (r Resource) Validate() error {
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if !r.IsValid() {
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return fmt.Errorf("invalid resource")
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}
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return nil
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}
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// parseResource - parses string to Resource.
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func parseResource(s string) (Resource, error) {
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if !strings.HasPrefix(s, ResourceARNPrefix) {
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return Resource{}, fmt.Errorf("invalid resource '%v'", s)
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}
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pattern := strings.TrimPrefix(s, ResourceARNPrefix)
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tokens := strings.SplitN(pattern, "/", 2)
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bucketName := tokens[0]
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if bucketName == "" {
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return Resource{}, fmt.Errorf("invalid resource format '%v'", s)
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}
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return Resource{
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BucketName: bucketName,
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Pattern: pattern,
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}, nil
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}
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// NewResource - creates new resource.
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func NewResource(bucketName, keyName string) Resource {
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pattern := bucketName
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if keyName != "" {
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if !strings.HasPrefix(keyName, "/") {
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pattern += "/"
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}
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pattern += keyName
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}
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return Resource{
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BucketName: bucketName,
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Pattern: pattern,
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}
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}
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