Add option to policy info API to return create/mod timestamps (#13796)

- This introduces a new admin API with a query parameter (v=2) to return a
response with the timestamps

- Older API still works for compatibility/smooth transition in console

cmd/admin-handlers-users.go

@@ -1198,6 +1198,16 @@ func (a adminAPIHandlers) AccountInfoHandler(w http.ResponseWriter, r *http.Requ
 }
 
 // InfoCannedPolicy - GET /minio/admin/v3/info-canned-policy?name={policyName}
+//
+// Newer API response with policy timestamps is returned with query parameter
+// `v=2` like:
+//
+// GET /minio/admin/v3/info-canned-policy?name={policyName}&v=2
+//
+// The newer API will eventually become the default (and only) one. The older
+// response is to return only the policy JSON. The newer response returns
+// timestamps along with the policy JSON. Both versions are supported for now,
+// for smooth transition to new API.
 func (a adminAPIHandlers) InfoCannedPolicy(w http.ResponseWriter, r *http.Request) {
 	ctx := newContext(r, w, "InfoCannedPolicy")
 
@@ -1208,13 +1218,36 @@ func (a adminAPIHandlers) InfoCannedPolicy(w http.ResponseWriter, r *http.Reques
 		return
 	}
 
-	policy, err := globalIAMSys.InfoPolicy(mux.Vars(r)["name"])
+	name := mux.Vars(r)["name"]
+	policies := newMappedPolicy(name).toSlice()
+	if len(policies) != 1 {
+		writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, errTooManyPolicies), r.URL)
+		return
+	}
+
+	policyDoc, err := globalIAMSys.InfoPolicy(name)
 	if err != nil {
 		writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, err), r.URL)
 		return
 	}
 
-	buf, err := json.MarshalIndent(policy, "", " ")
+	// Is the new API version being requested?
+	infoPolicyAPIVersion := r.Form.Get("v")
+	if infoPolicyAPIVersion == "2" {
+		buf, err := json.MarshalIndent(policyDoc, "", " ")
+		if err != nil {
+			writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, err), r.URL)
+			return
+		}
+		w.Write(buf)
+		return
+	} else if infoPolicyAPIVersion != "" {
+		writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, errors.New("invalid version parameter 'v' supplied")), r.URL)
+		return
+	}
+
+	// Return the older API response value of just the policy json.
+	buf, err := json.MarshalIndent(policyDoc.Policy, "", " ")
 	if err != nil {
 		writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, err), r.URL)
 		return

cmd/config-common.go

@@ -29,26 +29,31 @@ import (
 
 var errConfigNotFound = errors.New("config file not found")
 
-func readConfig(ctx context.Context, objAPI ObjectLayer, configFile string) ([]byte, error) {
+func readConfigWithMetadata(ctx context.Context, objAPI ObjectLayer, configFile string) ([]byte, ObjectInfo, error) {
 	r, err := objAPI.GetObjectNInfo(ctx, minioMetaBucket, configFile, nil, http.Header{}, readLock, ObjectOptions{})
 	if err != nil {
 		// Treat object not found as config not found.
 		if isErrObjectNotFound(err) {
-			return nil, errConfigNotFound
+			return nil, ObjectInfo{}, errConfigNotFound
 		}
 
-		return nil, err
+		return nil, ObjectInfo{}, err
 	}
 	defer r.Close()
 
 	buf, err := ioutil.ReadAll(r)
 	if err != nil {
-		return nil, err
+		return nil, ObjectInfo{}, err
 	}
 	if len(buf) == 0 {
-		return nil, errConfigNotFound
+		return nil, ObjectInfo{}, errConfigNotFound
 	}
-	return buf, nil
+	return buf, r.ObjInfo, nil
+}
+
+func readConfig(ctx context.Context, objAPI ObjectLayer, configFile string) ([]byte, error) {
+	buf, _, err := readConfigWithMetadata(ctx, objAPI, configFile)
+	return buf, err
 }
 
 type objectDeleter interface {

cmd/iam-dummy-store.go

@@ -22,7 +22,6 @@ import (
 	"sync"
 
 	"github.com/minio/minio/internal/auth"
-	iampolicy "github.com/minio/pkg/iam/policy"
 )
 
 type iamDummyStore struct {
@@ -64,7 +63,7 @@ func (ids *iamDummyStore) migrateBackendFormat(context.Context) error {
 	return nil
 }
 
-func (ids *iamDummyStore) loadPolicyDoc(ctx context.Context, policy string, m map[string]iampolicy.Policy) error {
+func (ids *iamDummyStore) loadPolicyDoc(ctx context.Context, policy string, m map[string]PolicyDoc) error {
 	v, ok := ids.iamPolicyDocsMap[policy]
 	if !ok {
 		return errNoSuchPolicy
@@ -73,7 +72,7 @@ func (ids *iamDummyStore) loadPolicyDoc(ctx context.Context, policy string, m ma
 	return nil
 }
 
-func (ids *iamDummyStore) loadPolicyDocs(ctx context.Context, m map[string]iampolicy.Policy) error {
+func (ids *iamDummyStore) loadPolicyDocs(ctx context.Context, m map[string]PolicyDoc) error {
 	for k, v := range ids.iamPolicyDocsMap {
 		m[k] = v
 	}
@@ -154,7 +153,7 @@ func (ids *iamDummyStore) deleteIAMConfig(ctx context.Context, path string) erro
 	return nil
 }
 
-func (ids *iamDummyStore) savePolicyDoc(ctx context.Context, policyName string, p iampolicy.Policy) error {
+func (ids *iamDummyStore) savePolicyDoc(ctx context.Context, policyName string, p PolicyDoc) error {
 	return nil
 }
 

cmd/iam-etcd-store.go

@@ -32,7 +32,6 @@ import (
 	"github.com/minio/minio/internal/config"
 	"github.com/minio/minio/internal/kms"
 	"github.com/minio/minio/internal/logger"
-	iampolicy "github.com/minio/pkg/iam/policy"
 	"go.etcd.io/etcd/api/v3/mvccpb"
 	etcd "go.etcd.io/etcd/client/v3"
 )
@@ -115,7 +114,7 @@ func (ies *IAMEtcdStore) saveIAMConfig(ctx context.Context, item interface{}, it
 	return saveKeyEtcd(ctx, ies.client, itemPath, data, opts...)
 }
 
-func getIAMConfig(item interface{}, data []byte, itemPath string) error {
+func decryptData(data []byte, itemPath string) ([]byte, error) {
 	var err error
 	if !utf8.Valid(data) && GlobalKMS != nil {
 		data, err = config.DecryptBytes(GlobalKMS, data, kms.Context{
@@ -127,11 +126,19 @@ func getIAMConfig(item interface{}, data []byte, itemPath string) error {
 			data, err = config.DecryptBytes(GlobalKMS, data, kms.Context{
 				minioMetaBucket: itemPath,
 			})
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+	return data, nil
+}
+
+func getIAMConfig(item interface{}, data []byte, itemPath string) error {
+	data, err := decryptData(data, itemPath)
 	if err != nil {
 		return err
 	}
-		}
-	}
 	var json = jsoniter.ConfigCompatibleWithStandardLibrary
 	return json.Unmarshal(data, item)
 }
@@ -144,6 +151,14 @@ func (ies *IAMEtcdStore) loadIAMConfig(ctx context.Context, item interface{}, pa
 	return getIAMConfig(item, data, path)
 }
 
+func (ies *IAMEtcdStore) loadIAMConfigBytes(ctx context.Context, path string) ([]byte, error) {
+	data, err := readKeyEtcd(ctx, ies.client, path)
+	if err != nil {
+		return nil, err
+	}
+	return decryptData(data, path)
+}
+
 func (ies *IAMEtcdStore) deleteIAMConfig(ctx context.Context, path string) error {
 	return deleteKeyEtcd(ctx, ies.client, path)
 }
@@ -263,34 +278,46 @@ func (ies *IAMEtcdStore) migrateBackendFormat(ctx context.Context) error {
 	return ies.migrateToV1(ctx)
 }
 
-func (ies *IAMEtcdStore) loadPolicyDoc(ctx context.Context, policy string, m map[string]iampolicy.Policy) error {
-	var p iampolicy.Policy
-	err := ies.loadIAMConfig(ctx, &p, getPolicyDocPath(policy))
+func (ies *IAMEtcdStore) loadPolicyDoc(ctx context.Context, policy string, m map[string]PolicyDoc) error {
+	data, err := ies.loadIAMConfigBytes(ctx, getPolicyDocPath(policy))
 	if err != nil {
 		if err == errConfigNotFound {
 			return errNoSuchPolicy
 		}
 		return err
 	}
+
+	var p PolicyDoc
+	err = p.parseJSON(data)
+	if err != nil {
+		return err
+	}
+
 	m[policy] = p
 	return nil
 }
 
-func (ies *IAMEtcdStore) getPolicyDocKV(ctx context.Context, kvs *mvccpb.KeyValue, m map[string]iampolicy.Policy) error {
-	var p iampolicy.Policy
-	err := getIAMConfig(&p, kvs.Value, string(kvs.Key))
+func (ies *IAMEtcdStore) getPolicyDocKV(ctx context.Context, kvs *mvccpb.KeyValue, m map[string]PolicyDoc) error {
+	data, err := decryptData(kvs.Value, string(kvs.Key))
 	if err != nil {
 		if err == errConfigNotFound {
 			return errNoSuchPolicy
 		}
 		return err
 	}
+
+	var p PolicyDoc
+	err = p.parseJSON(data)
+	if err != nil {
+		return err
+	}
+
 	policy := extractPathPrefixAndSuffix(string(kvs.Key), iamConfigPoliciesPrefix, path.Base(string(kvs.Key)))
 	m[policy] = p
 	return nil
 }
 
-func (ies *IAMEtcdStore) loadPolicyDocs(ctx context.Context, m map[string]iampolicy.Policy) error {
+func (ies *IAMEtcdStore) loadPolicyDocs(ctx context.Context, m map[string]PolicyDoc) error {
 	ctx, cancel := context.WithTimeout(ctx, defaultContextTimeout)
 	defer cancel()
 	//  Retrieve all keys and values to avoid too many calls to etcd in case of
@@ -473,7 +500,7 @@ func (ies *IAMEtcdStore) loadMappedPolicies(ctx context.Context, userType IAMUse
 
 }
 
-func (ies *IAMEtcdStore) savePolicyDoc(ctx context.Context, policyName string, p iampolicy.Policy) error {
+func (ies *IAMEtcdStore) savePolicyDoc(ctx context.Context, policyName string, p PolicyDoc) error {
 	return ies.saveIAMConfig(ctx, &p, getPolicyDocPath(policyName))
 }
 

cmd/iam-object-store.go

@@ -29,7 +29,6 @@ import (
 	"github.com/minio/minio/internal/config"
 	"github.com/minio/minio/internal/kms"
 	"github.com/minio/minio/internal/logger"
-	iampolicy "github.com/minio/pkg/iam/policy"
 )
 
 // IAMObjectStore implements IAMStorageAPI
@@ -218,19 +217,27 @@ func (iamOS *IAMObjectStore) saveIAMConfig(ctx context.Context, item interface{}
 	return saveConfig(ctx, iamOS.objAPI, objPath, data)
 }
 
-func (iamOS *IAMObjectStore) loadIAMConfig(ctx context.Context, item interface{}, objPath string) error {
-	data, err := readConfig(ctx, iamOS.objAPI, objPath)
+func (iamOS *IAMObjectStore) loadIAMConfigBytesWithMetadata(ctx context.Context, objPath string) ([]byte, ObjectInfo, error) {
+	data, meta, err := readConfigWithMetadata(ctx, iamOS.objAPI, objPath)
 	if err != nil {
-		return err
+		return nil, meta, err
 	}
 	if !utf8.Valid(data) && GlobalKMS != nil {
 		data, err = config.DecryptBytes(GlobalKMS, data, kms.Context{
 			minioMetaBucket: path.Join(minioMetaBucket, objPath),
 		})
 		if err != nil {
-			return err
+			return nil, meta, err
 		}
 	}
+	return data, meta, nil
+}
+
+func (iamOS *IAMObjectStore) loadIAMConfig(ctx context.Context, item interface{}, objPath string) error {
+	data, _, err := iamOS.loadIAMConfigBytesWithMetadata(ctx, objPath)
+	if err != nil {
+		return err
+	}
 	var json = jsoniter.ConfigCompatibleWithStandardLibrary
 	return json.Unmarshal(data, item)
 }
@@ -239,20 +246,34 @@ func (iamOS *IAMObjectStore) deleteIAMConfig(ctx context.Context, path string) e
 	return deleteConfig(ctx, iamOS.objAPI, path)
 }
 
-func (iamOS *IAMObjectStore) loadPolicyDoc(ctx context.Context, policy string, m map[string]iampolicy.Policy) error {
-	var p iampolicy.Policy
-	err := iamOS.loadIAMConfig(ctx, &p, getPolicyDocPath(policy))
+func (iamOS *IAMObjectStore) loadPolicyDoc(ctx context.Context, policy string, m map[string]PolicyDoc) error {
+	data, objInfo, err := iamOS.loadIAMConfigBytesWithMetadata(ctx, getPolicyDocPath(policy))
 	if err != nil {
 		if err == errConfigNotFound {
 			return errNoSuchPolicy
 		}
 		return err
 	}
+
+	var p PolicyDoc
+	err = p.parseJSON(data)
+	if err != nil {
+		return err
+	}
+
+	if p.Version == 0 {
+		// This means that policy was in the old version (without any
+		// timestamp info). We fetch the mod time of the file and save
+		// that as create and update date.
+		p.CreateDate = objInfo.ModTime
+		p.UpdateDate = objInfo.ModTime
+	}
+
 	m[policy] = p
 	return nil
 }
 
-func (iamOS *IAMObjectStore) loadPolicyDocs(ctx context.Context, m map[string]iampolicy.Policy) error {
+func (iamOS *IAMObjectStore) loadPolicyDocs(ctx context.Context, m map[string]PolicyDoc) error {
 	for item := range listIAMConfigItems(ctx, iamOS.objAPI, iamConfigPoliciesPrefix) {
 		if item.Err != nil {
 			return item.Err
@@ -385,7 +406,7 @@ func (iamOS *IAMObjectStore) loadMappedPolicies(ctx context.Context, userType IA
 	return nil
 }
 
-func (iamOS *IAMObjectStore) savePolicyDoc(ctx context.Context, policyName string, p iampolicy.Policy) error {
+func (iamOS *IAMObjectStore) savePolicyDoc(ctx context.Context, policyName string, p PolicyDoc) error {
 	return iamOS.saveIAMConfig(ctx, &p, getPolicyDocPath(policyName))
 }
 

cmd/iam-store.go

@@ -24,8 +24,10 @@ import (
 	"errors"
 	"fmt"
 	"strings"
+	"time"
 
 	"github.com/dustin/go-humanize"
+	jsoniter "github.com/json-iterator/go"
 	"github.com/minio/madmin-go"
 	"github.com/minio/minio-go/v7/pkg/set"
 	"github.com/minio/minio/internal/auth"
@@ -169,6 +171,64 @@ func newMappedPolicy(policy string) MappedPolicy {
 	return MappedPolicy{Version: 1, Policies: policy}
 }
 
+// PolicyDoc represents an IAM policy with some metadata.
+type PolicyDoc struct {
+	Version    int `json:",omitempty"`
+	Policy     iampolicy.Policy
+	CreateDate time.Time `json:",omitempty"`
+	UpdateDate time.Time `json:",omitempty"`
+}
+
+func newPolicyDoc(p iampolicy.Policy) PolicyDoc {
+	now := UTCNow().Round(time.Millisecond)
+	return PolicyDoc{
+		Version:    1,
+		Policy:     p,
+		CreateDate: now,
+		UpdateDate: now,
+	}
+}
+
+// defaultPolicyDoc - used to wrap a default policy as PolicyDoc.
+func defaultPolicyDoc(p iampolicy.Policy) PolicyDoc {
+	return PolicyDoc{
+		Version: 1,
+		Policy:  p,
+	}
+}
+
+func (d *PolicyDoc) update(p iampolicy.Policy) {
+	now := UTCNow().Round(time.Millisecond)
+	d.UpdateDate = now
+	if d.CreateDate.IsZero() {
+		d.CreateDate = now
+	}
+	d.Policy = p
+}
+
+// parseJSON parses both the old and the new format for storing policy
+// definitions.
+//
+// The on-disk format of policy definitions has changed (around early 12/2021)
+// from iampolicy.Policy to PolicyDoc. To avoid a migration, loading supports
+// both the old and the new formats.
+func (d *PolicyDoc) parseJSON(data []byte) error {
+	var json = jsoniter.ConfigCompatibleWithStandardLibrary
+	var doc PolicyDoc
+	err := json.Unmarshal(data, &doc)
+	if err != nil {
+		err2 := json.Unmarshal(data, &doc.Policy)
+		if err2 != nil {
+			// Just return the first error.
+			return err
+		}
+		d.Policy = doc.Policy
+		return nil
+	}
+	*d = doc
+	return nil
+}
+
 // key options
 type options struct {
 	ttl int64 // expiry in seconds
@@ -182,7 +242,7 @@ type iamWatchEvent struct {
 // iamCache contains in-memory cache of IAM data.
 type iamCache struct {
 	// map of policy names to policy definitions
-	iamPolicyDocsMap map[string]iampolicy.Policy
+	iamPolicyDocsMap map[string]PolicyDoc
 	// map of usernames to credentials
 	iamUsersMap map[string]auth.Credentials
 	// map of group names to group info
@@ -197,7 +257,7 @@ type iamCache struct {
 
 func newIamCache() *iamCache {
 	return &iamCache{
-		iamPolicyDocsMap:        map[string]iampolicy.Policy{},
+		iamPolicyDocsMap:        map[string]PolicyDoc{},
 		iamUsersMap:             map[string]auth.Credentials{},
 		iamGroupsMap:            map[string]GroupInfo{},
 		iamUserGroupMemberships: map[string]set.StringSet{},
@@ -332,8 +392,8 @@ type IAMStorageAPI interface {
 
 	getUsersSysType() UsersSysType
 
-	loadPolicyDoc(ctx context.Context, policy string, m map[string]iampolicy.Policy) error
-	loadPolicyDocs(ctx context.Context, m map[string]iampolicy.Policy) error
+	loadPolicyDoc(ctx context.Context, policy string, m map[string]PolicyDoc) error
+	loadPolicyDocs(ctx context.Context, m map[string]PolicyDoc) error
 
 	loadUser(ctx context.Context, user string, userType IAMUserType, m map[string]auth.Credentials) error
 	loadUsers(ctx context.Context, userType IAMUserType, m map[string]auth.Credentials) error
@@ -348,7 +408,7 @@ type IAMStorageAPI interface {
 	loadIAMConfig(ctx context.Context, item interface{}, path string) error
 	deleteIAMConfig(ctx context.Context, path string) error
 
-	savePolicyDoc(ctx context.Context, policyName string, p iampolicy.Policy) error
+	savePolicyDoc(ctx context.Context, policyName string, p PolicyDoc) error
 	saveMappedPolicy(ctx context.Context, name string, userType IAMUserType, isGroup bool, mp MappedPolicy, opts ...options) error
 	saveUserIdentity(ctx context.Context, name string, userType IAMUserType, u UserIdentity, opts ...options) error
 	saveGroupInfo(ctx context.Context, group string, gi GroupInfo) error
@@ -366,10 +426,10 @@ type iamStorageWatcher interface {
 }
 
 // Set default canned policies only if not already overridden by users.
-func setDefaultCannedPolicies(policies map[string]iampolicy.Policy) {
+func setDefaultCannedPolicies(policies map[string]PolicyDoc) {
 	for _, v := range iampolicy.DefaultPolicies {
 		if _, ok := policies[v.Name]; !ok {
-			policies[v.Name] = v.Definition
+			policies[v.Name] = defaultPolicyDoc(v.Definition)
 		}
 	}
 }
@@ -947,13 +1007,31 @@ func (store *IAMStoreSys) GetPolicy(name string) (iampolicy.Policy, error) {
 		}
 		v, ok := cache.iamPolicyDocsMap[policy]
 		if !ok {
-			return v, errNoSuchPolicy
+			return v.Policy, errNoSuchPolicy
 		}
-		combinedPolicy = combinedPolicy.Merge(v)
+		combinedPolicy = combinedPolicy.Merge(v.Policy)
 	}
 	return combinedPolicy, nil
 }
 
+// GetPolicyDoc - gets the policy doc which has the policy and some metadata.
+// Exactly one policy must be specified here.
+func (store *IAMStoreSys) GetPolicyDoc(name string) (r PolicyDoc, err error) {
+	name = strings.TrimSpace(name)
+	if name == "" {
+		return r, errInvalidArgument
+	}
+
+	cache := store.rlock()
+	defer store.runlock()
+
+	v, ok := cache.iamPolicyDocsMap[name]
+	if !ok {
+		return r, errNoSuchPolicy
+	}
+	return v, nil
+}
+
 // SetPolicy - creates a policy with name.
 func (store *IAMStoreSys) SetPolicy(ctx context.Context, name string, policy iampolicy.Policy) error {
 
@@ -964,11 +1042,21 @@ func (store *IAMStoreSys) SetPolicy(ctx context.Context, name string, policy iam
 	cache := store.lock()
 	defer store.unlock()
 
-	if err := store.savePolicyDoc(ctx, name, policy); err != nil {
+	var (
+		d  PolicyDoc
+		ok bool
+	)
+	if d, ok = cache.iamPolicyDocsMap[name]; ok {
+		d.update(policy)
+	} else {
+		d = newPolicyDoc(policy)
+	}
+
+	if err := store.savePolicyDoc(ctx, name, d); err != nil {
 		return err
 	}
 
-	cache.iamPolicyDocsMap[name] = policy
+	cache.iamPolicyDocsMap[name] = d
 	return nil
 
 }
@@ -979,7 +1067,7 @@ func (store *IAMStoreSys) ListPolicies(ctx context.Context, bucketName string) (
 	cache := store.lock()
 	defer store.unlock()
 
-	m := map[string]iampolicy.Policy{}
+	m := map[string]PolicyDoc{}
 	err := store.loadPolicyDocs(ctx, m)
 	if err != nil {
 		return nil, err
@@ -992,8 +1080,8 @@ func (store *IAMStoreSys) ListPolicies(ctx context.Context, bucketName string) (
 
 	ret := map[string]iampolicy.Policy{}
 	for k, v := range m {
-		if bucketName == "" || v.MatchResource(bucketName) {
-			ret[k] = v
+		if bucketName == "" || v.Policy.MatchResource(bucketName) {
+			ret[k] = v.Policy
 		}
 	}
 
@@ -1011,9 +1099,9 @@ func filterPolicies(cache *iamCache, policyName string, bucketName string) (stri
 		}
 		p, found := cache.iamPolicyDocsMap[policy]
 		if found {
-			if bucketName == "" || p.MatchResource(bucketName) {
+			if bucketName == "" || p.Policy.MatchResource(bucketName) {
 				policies = append(policies, policy)
-				combinedPolicy = combinedPolicy.Merge(p)
+				combinedPolicy = combinedPolicy.Merge(p.Policy)
 			}
 		}
 	}

cmd/iam.go

@@ -477,13 +477,28 @@ func (sys *IAMSys) DeletePolicy(ctx context.Context, policyName string, notifyPe
 	return nil
 }
 
-// InfoPolicy - expands the canned policy into its JSON structure.
-func (sys *IAMSys) InfoPolicy(policyName string) (iampolicy.Policy, error) {
+// InfoPolicy - returns the policy definition with some metadata.
+func (sys *IAMSys) InfoPolicy(policyName string) (*madmin.PolicyInfo, error) {
 	if !sys.Initialized() {
-		return iampolicy.Policy{}, errServerNotInitialized
+		return nil, errServerNotInitialized
 	}
 
-	return sys.store.GetPolicy(policyName)
+	d, err := sys.store.GetPolicyDoc(policyName)
+	if err != nil {
+		return nil, err
+	}
+
+	pdata, err := json.Marshal(d.Policy)
+	if err != nil {
+		return nil, err
+	}
+
+	return &madmin.PolicyInfo{
+		PolicyName: policyName,
+		Policy:     pdata,
+		CreateDate: d.CreateDate,
+		UpdateDate: d.UpdateDate,
+	}, nil
 }
 
 // ListPolicies - lists all canned policies.

cmd/typed-errors.go

@@ -84,6 +84,10 @@ var errNoSuchPolicy = errors.New("Specified canned policy does not exist")
 // error returned when policy to be deleted is in use.
 var errPolicyInUse = errors.New("Specified policy is in use and cannot be deleted.")
 
+// error returned when more than a single policy is specified when only one is
+// expectd.
+var errTooManyPolicies = errors.New("Only a single policy may be specified here.")
+
 // error returned in IAM subsystem when an external users systems is configured.
 var errIAMActionNotAllowed = errors.New("Specified IAM action is not allowed")