216 lines
5.2 KiB
Go
216 lines
5.2 KiB
Go
// Copyright 2016 The etcd Authors
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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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package auth
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import (
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"bytes"
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"sort"
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"github.com/coreos/etcd/auth/authpb"
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"github.com/coreos/etcd/mvcc/backend"
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)
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// isSubset returns true if a is a subset of b.
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// If a is a prefix of b, then a is a subset of b.
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// Given intervals [a1,a2) and [b1,b2), is
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// the a interval a subset of b?
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func isSubset(a, b *rangePerm) bool {
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switch {
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case len(a.end) == 0 && len(b.end) == 0:
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// a, b are both keys
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return bytes.Equal(a.begin, b.begin)
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case len(b.end) == 0:
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// b is a key, a is a range
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return false
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case len(a.end) == 0:
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// a is a key, b is a range. need b1 <= a1 and a1 < b2
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return bytes.Compare(b.begin, a.begin) <= 0 && bytes.Compare(a.begin, b.end) < 0
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default:
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// both are ranges. need b1 <= a1 and a2 <= b2
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return bytes.Compare(b.begin, a.begin) <= 0 && bytes.Compare(a.end, b.end) <= 0
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}
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}
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func isRangeEqual(a, b *rangePerm) bool {
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return bytes.Equal(a.begin, b.begin) && bytes.Equal(a.end, b.end)
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}
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// mergeRangePerms merges adjacent rangePerms.
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func mergeRangePerms(perms []*rangePerm) (rs []*rangePerm) {
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if len(perms) < 2 {
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return perms
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}
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sort.Sort(RangePermSliceByBegin(perms))
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// initialize with first rangePerm
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rs = append(rs, perms[0])
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// merge in-place from 2nd
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for i := 1; i < len(perms); i++ {
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rp := rs[len(rs)-1]
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// skip duplicate range
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if isRangeEqual(rp, perms[i]) {
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continue
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}
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// merge ["a", "") with ["a", "c")
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if bytes.Equal(rp.begin, perms[i].begin) && len(rp.end) == 0 && len(perms[i].end) > 0 {
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rp.end = perms[i].end
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continue
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}
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// do not merge ["a", "b") with ["b", "")
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if bytes.Equal(rp.end, perms[i].begin) && len(perms[i].end) == 0 {
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rs = append(rs, perms[i])
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continue
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}
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// rp.end < perms[i].begin; found beginning of next range
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if bytes.Compare(rp.end, perms[i].begin) < 0 {
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rs = append(rs, perms[i])
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continue
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}
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rp.end = getMax(rp.end, perms[i].end)
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}
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return
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}
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func getMax(a, b []byte) []byte {
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if bytes.Compare(a, b) > 0 {
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return a
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}
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return b
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}
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func getMergedPerms(tx backend.BatchTx, userName string) *unifiedRangePermissions {
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user := getUser(tx, userName)
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if user == nil {
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plog.Errorf("invalid user name %s", userName)
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return nil
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}
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var readPerms, writePerms []*rangePerm
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for _, roleName := range user.Roles {
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role := getRole(tx, roleName)
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if role == nil {
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continue
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}
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for _, perm := range role.KeyPermission {
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rp := &rangePerm{begin: perm.Key, end: perm.RangeEnd}
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switch perm.PermType {
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case authpb.READWRITE:
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readPerms = append(readPerms, rp)
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writePerms = append(writePerms, rp)
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case authpb.READ:
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readPerms = append(readPerms, rp)
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case authpb.WRITE:
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writePerms = append(writePerms, rp)
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}
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}
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}
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return &unifiedRangePermissions{
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readPerms: mergeRangePerms(readPerms),
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writePerms: mergeRangePerms(writePerms),
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}
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}
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func checkKeyPerm(cachedPerms *unifiedRangePermissions, key, rangeEnd []byte, permtyp authpb.Permission_Type) bool {
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var tocheck []*rangePerm
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switch permtyp {
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case authpb.READ:
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tocheck = cachedPerms.readPerms
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case authpb.WRITE:
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tocheck = cachedPerms.writePerms
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default:
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plog.Panicf("unknown auth type: %v", permtyp)
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}
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requiredPerm := &rangePerm{begin: key, end: rangeEnd}
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for _, perm := range tocheck {
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if isSubset(requiredPerm, perm) {
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return true
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}
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}
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return false
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}
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func (as *authStore) isRangeOpPermitted(tx backend.BatchTx, userName string, key, rangeEnd []byte, permtyp authpb.Permission_Type) bool {
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// assumption: tx is Lock()ed
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_, ok := as.rangePermCache[userName]
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if !ok {
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perms := getMergedPerms(tx, userName)
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if perms == nil {
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plog.Errorf("failed to create a unified permission of user %s", userName)
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return false
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}
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as.rangePermCache[userName] = perms
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}
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return checkKeyPerm(as.rangePermCache[userName], key, rangeEnd, permtyp)
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}
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func (as *authStore) clearCachedPerm() {
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as.rangePermCache = make(map[string]*unifiedRangePermissions)
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}
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func (as *authStore) invalidateCachedPerm(userName string) {
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delete(as.rangePermCache, userName)
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}
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type unifiedRangePermissions struct {
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// readPerms[i] and readPerms[j] (i != j) don't overlap
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readPerms []*rangePerm
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// writePerms[i] and writePerms[j] (i != j) don't overlap, too
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writePerms []*rangePerm
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}
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type rangePerm struct {
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begin, end []byte
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}
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type RangePermSliceByBegin []*rangePerm
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func (slice RangePermSliceByBegin) Len() int {
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return len(slice)
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}
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func (slice RangePermSliceByBegin) Less(i, j int) bool {
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switch bytes.Compare(slice[i].begin, slice[j].begin) {
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case 0: // begin(i) == begin(j)
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return bytes.Compare(slice[i].end, slice[j].end) == -1
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case -1: // begin(i) < begin(j)
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return true
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default:
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return false
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}
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}
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func (slice RangePermSliceByBegin) Swap(i, j int) {
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slice[i], slice[j] = slice[j], slice[i]
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}
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