[v9] Make tsh db ls lists available db users. (#10458)

lib/services/role.go

@@ -862,6 +862,110 @@ func NewRoleSet(roles ...types.Role) RoleSet {
 // RoleSet is a set of roles that implements access control functionality
 type RoleSet []types.Role
 
+// EnumerationResult is a result of enumerating a role set against some property, e.g. allowed names or logins.
+type EnumerationResult struct {
+	allowedDeniedMap map[string]bool
+	wildcardAllowed  bool
+	wildcardDenied   bool
+}
+
+func (result *EnumerationResult) filtered(value bool) []string {
+	var filtered []string
+
+	for entity, allow := range result.allowedDeniedMap {
+		if allow == value {
+			filtered = append(filtered, entity)
+		}
+	}
+
+	sort.Strings(filtered)
+
+	return filtered
+}
+
+// Denied returns all explicitly denied users.
+func (result *EnumerationResult) Denied() []string {
+	return result.filtered(false)
+}
+
+// Allowed returns all known allowed users.
+func (result *EnumerationResult) Allowed() []string {
+	if result.WildcardDenied() {
+		return nil
+	}
+	return result.filtered(true)
+}
+
+// WildcardAllowed is true if there * username allowed for given rule set.
+func (result *EnumerationResult) WildcardAllowed() bool {
+	return result.wildcardAllowed && !result.wildcardDenied
+}
+
+// WildcardDenied is true if there * username deny for given rule set.
+func (result *EnumerationResult) WildcardDenied() bool {
+	return result.wildcardDenied
+}
+
+// NewEnumerationResult returns new EnumerationResult.
+func NewEnumerationResult() EnumerationResult {
+	return EnumerationResult{
+		allowedDeniedMap: map[string]bool{},
+		wildcardAllowed:  false,
+		wildcardDenied:   false,
+	}
+}
+
+// EnumerateDatabaseUsers works on a given role set to return a minimal description of allowed set of usernames.
+// It is biased towards *allowed* usernames; It is meant to describe what the user can do, rather than cannot do.
+// For that reason if the user isn't allowed to pick *any* entities, the output will be empty.
+//
+// In cases where * is listed in set of allowed users, it may be hard for users to figure out the expected username.
+// For this reason the parameter extraUsers provides an extra set of users to be checked against RoleSet.
+// This extra set of users may be sourced e.g. from user connection history.
+func (set RoleSet) EnumerateDatabaseUsers(database types.Database, extraUsers ...string) EnumerationResult {
+	result := NewEnumerationResult()
+
+	// gather users for checking from the roles, check wildcards.
+	var users []string
+	for _, role := range set {
+		wildcardAllowed := false
+		wildcardDenied := false
+
+		for _, user := range role.GetDatabaseUsers(types.Allow) {
+			if user == types.Wildcard {
+				wildcardAllowed = true
+			} else {
+				users = append(users, user)
+			}
+		}
+
+		for _, user := range role.GetDatabaseUsers(types.Deny) {
+			if user == types.Wildcard {
+				wildcardDenied = true
+			} else {
+				users = append(users, user)
+			}
+		}
+
+		result.wildcardDenied = result.wildcardDenied || wildcardDenied
+
+		if err := NewRoleSet(role).CheckAccess(database, AccessMFAParams{Verified: true}); err == nil {
+			result.wildcardAllowed = result.wildcardAllowed || wildcardAllowed
+		}
+
+	}
+
+	users = apiutils.Deduplicate(append(users, extraUsers...))
+
+	// check each individual user against the database.
+	for _, user := range users {
+		err := set.CheckAccess(database, AccessMFAParams{Verified: true}, &DatabaseUserMatcher{User: user})
+		result.allowedDeniedMap[user] = err == nil
+	}
+
+	return result
+}
+
 // MatchNamespace returns true if given list of namespace matches
 // target namespace, wildcard matches everything.
 func MatchNamespace(selectors []string, namespace string) (bool, string) {

lib/services/role_test.go

@@ -2680,6 +2680,128 @@ func TestCheckAccessToDatabaseUser(t *testing.T) {
 	}
 }
 
+func TestRoleSetEnumerateDatabaseUsers(t *testing.T) {
+	dbStage, err := types.NewDatabaseV3(types.Metadata{
+		Name:   "stage",
+		Labels: map[string]string{"env": "stage"},
+	}, types.DatabaseSpecV3{
+		Protocol: "protocol",
+		URI:      "uri",
+	})
+	require.NoError(t, err)
+	dbProd, err := types.NewDatabaseV3(types.Metadata{
+		Name:   "prod",
+		Labels: map[string]string{"env": "prod"},
+	}, types.DatabaseSpecV3{
+		Protocol: "protocol",
+		URI:      "uri",
+	})
+	require.NoError(t, err)
+	roleDevStage := &types.RoleV5{
+		Metadata: types.Metadata{Name: "dev-stage", Namespace: apidefaults.Namespace},
+		Spec: types.RoleSpecV5{
+			Allow: types.RoleConditions{
+				Namespaces:     []string{apidefaults.Namespace},
+				DatabaseLabels: types.Labels{"env": []string{"stage"}},
+				DatabaseUsers:  []string{types.Wildcard},
+			},
+			Deny: types.RoleConditions{
+				Namespaces:    []string{apidefaults.Namespace},
+				DatabaseUsers: []string{"superuser"},
+			},
+		},
+	}
+	roleDevProd := &types.RoleV5{
+		Metadata: types.Metadata{Name: "dev-prod", Namespace: apidefaults.Namespace},
+		Spec: types.RoleSpecV5{
+			Allow: types.RoleConditions{
+				Namespaces:     []string{apidefaults.Namespace},
+				DatabaseLabels: types.Labels{"env": []string{"prod"}},
+				DatabaseUsers:  []string{"dev"},
+			},
+		},
+	}
+
+	roleNoDBAccess := &types.RoleV5{
+		Metadata: types.Metadata{Name: "no_db_access", Namespace: apidefaults.Namespace},
+		Spec: types.RoleSpecV5{
+			Deny: types.RoleConditions{
+				Namespaces:    []string{apidefaults.Namespace},
+				DatabaseUsers: []string{"*"},
+				DatabaseNames: []string{"*"},
+			},
+		},
+	}
+
+	roleAllowDenySame := &types.RoleV5{
+		Metadata: types.Metadata{Name: "allow_deny_same", Namespace: apidefaults.Namespace},
+		Spec: types.RoleSpecV5{
+			Allow: types.RoleConditions{
+				Namespaces:    []string{apidefaults.Namespace},
+				DatabaseUsers: []string{"superuser"},
+			},
+			Deny: types.RoleConditions{
+				Namespaces:    []string{apidefaults.Namespace},
+				DatabaseUsers: []string{"superuser"},
+			},
+		},
+	}
+
+	testCases := []struct {
+		name       string
+		roles      RoleSet
+		server     types.Database
+		enumResult EnumerationResult
+	}{
+		{
+			name:   "deny overrides allow",
+			roles:  RoleSet{roleAllowDenySame},
+			server: dbStage,
+			enumResult: EnumerationResult{
+				allowedDeniedMap: map[string]bool{"superuser": false},
+				wildcardAllowed:  false,
+				wildcardDenied:   false,
+			},
+		},
+		{
+			name:   "developer allowed any username in stage database except superuser",
+			roles:  RoleSet{roleDevStage, roleDevProd},
+			server: dbStage,
+			enumResult: EnumerationResult{
+				allowedDeniedMap: map[string]bool{"dev": true, "superuser": false},
+				wildcardAllowed:  true,
+				wildcardDenied:   false,
+			},
+		},
+		{
+			name:   "developer allowed only specific username/database in prod database",
+			roles:  RoleSet{roleDevStage, roleDevProd},
+			server: dbProd,
+			enumResult: EnumerationResult{
+				allowedDeniedMap: map[string]bool{"dev": true, "superuser": false},
+				wildcardAllowed:  false,
+				wildcardDenied:   false,
+			},
+		},
+		{
+			name:   "there may be users disallowed from all users",
+			roles:  RoleSet{roleDevStage, roleDevProd, roleNoDBAccess},
+			server: dbProd,
+			enumResult: EnumerationResult{
+				allowedDeniedMap: map[string]bool{"dev": false, "superuser": false},
+				wildcardAllowed:  false,
+				wildcardDenied:   true,
+			},
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			enumResult := tc.roles.EnumerateDatabaseUsers(tc.server)
+			require.Equal(t, tc.enumResult, enumResult)
+		})
+	}
+}
+
 func TestCheckDatabaseNamesAndUsers(t *testing.T) {
 	roleEmpty := &types.RoleV5{
 		Metadata: types.Metadata{Name: "roleA", Namespace: apidefaults.Namespace},

tool/tsh/db.go

@@ -30,6 +30,7 @@ import (
 	"github.com/gravitational/teleport/lib/client"
 	dbprofile "github.com/gravitational/teleport/lib/client/db"
 	"github.com/gravitational/teleport/lib/defaults"
+	"github.com/gravitational/teleport/lib/services"
 	"github.com/gravitational/teleport/lib/tlsca"
 	"github.com/gravitational/teleport/lib/utils"
 
@@ -50,11 +51,29 @@ func onListDatabases(cf *CLIConf) error {
 	if err != nil {
 		return trace.Wrap(err)
 	}
+
+	proxy, err := tc.ConnectToProxy(cf.Context)
+	if err != nil {
+		return trace.Wrap(err)
+	}
+
+	cluster, err := proxy.ConnectToCurrentCluster(cf.Context, false)
+	if err != nil {
+		return trace.Wrap(err)
+	}
+	defer cluster.Close()
+
 	// Retrieve profile to be able to show which databases user is logged into.
 	profile, err := client.StatusCurrent(cf.HomePath, cf.Proxy)
 	if err != nil {
 		return trace.Wrap(err)
 	}
+
+	roleSet, err := services.FetchRoles(profile.Roles, cluster, profile.Traits)
+	if err != nil {
+		return trace.Wrap(err)
+	}
+
 	sort.Slice(databases, func(i, j int) bool {
 		return databases[i].GetName() < databases[j].GetName()
 	})
@@ -63,7 +82,7 @@ func onListDatabases(cf *CLIConf) error {
 	if err != nil {
 		return trace.Wrap(err)
 	}
-	return trace.Wrap(showDatabases(cf.SiteName, databases, activeDatabases, cf.Format, cf.Verbose))
+	return trace.Wrap(showDatabases(cf.SiteName, databases, activeDatabases, roleSet, cf.Format, cf.Verbose))
 }
 
 // onDatabaseLogin implements "tsh db login" command.

tool/tsh/tsh.go

@@ -1648,11 +1648,31 @@ func showAppsAsText(apps []types.Application, active []tlsca.RouteToApp, verbose
 	}
 }
 
-func showDatabases(clusterFlag string, databases []types.Database, active []tlsca.RouteToDatabase, format string, verbose bool) error {
+func getUsersForDb(database types.Database, roleSet services.RoleSet) string {
+	dbUsers := roleSet.EnumerateDatabaseUsers(database)
+	allowed := dbUsers.Allowed()
+
+	if dbUsers.WildcardAllowed() {
+		// start the list with *
+		allowed = append([]string{types.Wildcard}, allowed...)
+	}
+
+	if len(allowed) == 0 {
+		return "(none)"
+	}
+
+	denied := dbUsers.Denied()
+	if len(denied) == 0 || !dbUsers.WildcardAllowed() {
+		return fmt.Sprintf("%v", allowed)
+	}
+	return fmt.Sprintf("%v, except: %v", allowed, denied)
+}
+
+func showDatabases(clusterFlag string, databases []types.Database, active []tlsca.RouteToDatabase, roleSet services.RoleSet, format string, verbose bool) error {
 	format = strings.ToLower(format)
 	switch format {
 	case teleport.Text, "":
-		showDatabasesAsText(clusterFlag, databases, active, verbose)
+		showDatabasesAsText(clusterFlag, databases, active, roleSet, verbose)
 	case teleport.JSON, teleport.YAML:
 		out, err := serializeDatabases(databases, format)
 		if err != nil {
@@ -1679,9 +1699,9 @@ func serializeDatabases(databases []types.Database, format string) (string, erro
 	return string(out), trace.Wrap(err)
 }
 
-func showDatabasesAsText(clusterFlag string, databases []types.Database, active []tlsca.RouteToDatabase, verbose bool) {
+func showDatabasesAsText(clusterFlag string, databases []types.Database, active []tlsca.RouteToDatabase, roleSet services.RoleSet, verbose bool) {
 	if verbose {
-		t := asciitable.MakeTable([]string{"Name", "Description", "Protocol", "Type", "URI", "Labels", "Connect", "Expires"})
+		t := asciitable.MakeTable([]string{"Name", "Description", "Protocol", "Type", "URI", "Allowed Users", "Labels", "Connect", "Expires"})
 		for _, database := range databases {
 			name := database.GetName()
 			var connect string
@@ -1691,12 +1711,14 @@ func showDatabasesAsText(clusterFlag string, databases []types.Database, active
 					connect = formatConnectCommand(clusterFlag, a)
 				}
 			}
+
 			t.AddRow([]string{
 				name,
 				database.GetDescription(),
 				database.GetProtocol(),
 				database.GetType(),
 				database.GetURI(),
+				getUsersForDb(database, roleSet),
 				database.LabelsString(),
 				connect,
 				database.Expiry().Format(constants.HumanDateFormatSeconds),
@@ -1717,11 +1739,12 @@ func showDatabasesAsText(clusterFlag string, databases []types.Database, active
 			rows = append(rows, []string{
 				name,
 				database.GetDescription(),
+				getUsersForDb(database, roleSet),
 				formatDatabaseLabels(database),
 				connect,
 			})
 		}
-		t := asciitable.MakeTableWithTruncatedColumn([]string{"Name", "Description", "Labels", "Connect"}, rows, "Labels")
+		t := asciitable.MakeTableWithTruncatedColumn([]string{"Name", "Description", "Allowed Users", "Labels", "Connect"}, rows, "Labels")
 		fmt.Println(t.AsBuffer().String())
 	}
 }