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role.go
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role.go
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/*
Copyright 2021 Gravitational, 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 services
import (
"context"
"encoding/json"
"fmt"
"regexp"
"sort"
"strings"
"time"
"github.com/aws/aws-sdk-go/aws/arn"
"github.com/google/uuid"
"github.com/gravitational/configure/cstrings"
"github.com/gravitational/trace"
log "github.com/sirupsen/logrus"
"github.com/vulcand/predicate"
"golang.org/x/crypto/ssh"
"golang.org/x/exp/slices"
"github.com/gravitational/teleport"
"github.com/gravitational/teleport/api/constants"
"github.com/gravitational/teleport/api/defaults"
"github.com/gravitational/teleport/api/types"
"github.com/gravitational/teleport/api/types/wrappers"
apiutils "github.com/gravitational/teleport/api/utils"
"github.com/gravitational/teleport/api/utils/keys"
"github.com/gravitational/teleport/lib/tlsca"
"github.com/gravitational/teleport/lib/utils"
awsutils "github.com/gravitational/teleport/lib/utils/aws"
"github.com/gravitational/teleport/lib/utils/parse"
)
// DefaultImplicitRules provides access to the default set of implicit rules
// assigned to all roles.
var DefaultImplicitRules = []types.Rule{
types.NewRule(types.KindNode, RO()),
types.NewRule(types.KindProxy, RO()),
types.NewRule(types.KindAuthServer, RO()),
types.NewRule(types.KindReverseTunnel, RO()),
types.NewRule(types.KindCertAuthority, ReadNoSecrets()),
types.NewRule(types.KindClusterAuthPreference, RO()),
types.NewRule(types.KindClusterName, RO()),
types.NewRule(types.KindSSHSession, RO()),
types.NewRule(types.KindAppServer, RO()),
types.NewRule(types.KindRemoteCluster, RO()),
types.NewRule(types.KindKubeServer, RO()),
types.NewRule(types.KindDatabaseServer, RO()),
types.NewRule(types.KindDatabase, RO()),
types.NewRule(types.KindApp, RO()),
types.NewRule(types.KindWindowsDesktopService, RO()),
types.NewRule(types.KindWindowsDesktop, RO()),
types.NewRule(types.KindKubernetesCluster, RO()),
types.NewRule(types.KindUsageEvent, []string{types.VerbCreate}),
}
// DefaultCertAuthorityRules provides access the minimal set of resources
// needed for a certificate authority to function.
var DefaultCertAuthorityRules = []types.Rule{
types.NewRule(types.KindSession, RO()),
types.NewRule(types.KindNode, RO()),
types.NewRule(types.KindAuthServer, RO()),
types.NewRule(types.KindReverseTunnel, RO()),
types.NewRule(types.KindCertAuthority, ReadNoSecrets()),
}
// ErrTrustedDeviceRequired is returned by AccessChecker when access to a
// resource requires a trusted device.
var ErrTrustedDeviceRequired = trace.AccessDenied("access to resource requires a trusted device")
// ErrSessionMFARequired is returned by AccessChecker when access to a resource
// requires an MFA check.
var ErrSessionMFARequired = trace.AccessDenied("access to resource requires MFA")
// ErrSessionMFANotRequired indicates that per session mfa will not grant
// access to a resource.
var ErrSessionMFANotRequired = trace.AccessDenied("MFA is not required to access resource")
// RoleNameForUser returns role name associated with a user.
func RoleNameForUser(name string) string {
return "user:" + name
}
// RoleNameForCertAuthority returns role name associated with a certificate
// authority.
func RoleNameForCertAuthority(name string) string {
return "ca:" + name
}
// NewImplicitRole is the default implicit role that gets added to all
// RoleSets.
func NewImplicitRole() types.Role {
return &types.RoleV6{
Kind: types.KindRole,
Version: types.V3,
Metadata: types.Metadata{
Name: constants.DefaultImplicitRole,
Namespace: defaults.Namespace,
},
Spec: types.RoleSpecV6{
Options: types.RoleOptions{
MaxSessionTTL: types.MaxDuration(),
// Explicitly disable options that default to true, otherwise the option
// will always be enabled, as this implicit role is part of every role set.
PortForwarding: types.NewBoolOption(false),
RecordSession: &types.RecordSession{
Desktop: types.NewBoolOption(false),
},
},
Allow: types.RoleConditions{
Namespaces: []string{defaults.Namespace},
Rules: types.CopyRulesSlice(DefaultImplicitRules),
},
},
}
}
// RoleForUser creates an admin role for a services.User.
//
// Used in tests only.
func RoleForUser(u types.User) types.Role {
role, _ := types.NewRole(RoleNameForUser(u.GetName()), types.RoleSpecV6{
Options: types.RoleOptions{
CertificateFormat: constants.CertificateFormatStandard,
MaxSessionTTL: types.NewDuration(defaults.MaxCertDuration),
PortForwarding: types.NewBoolOption(true),
ForwardAgent: types.NewBool(true),
BPF: defaults.EnhancedEvents(),
},
Allow: types.RoleConditions{
Namespaces: []string{defaults.Namespace},
NodeLabels: types.Labels{types.Wildcard: []string{types.Wildcard}},
AppLabels: types.Labels{types.Wildcard: []string{types.Wildcard}},
GroupLabels: types.Labels{types.Wildcard: []string{types.Wildcard}},
KubernetesLabels: types.Labels{types.Wildcard: []string{types.Wildcard}},
DatabaseServiceLabels: types.Labels{types.Wildcard: []string{types.Wildcard}},
DatabaseLabels: types.Labels{types.Wildcard: []string{types.Wildcard}},
Rules: []types.Rule{
types.NewRule(types.KindRole, RW()),
types.NewRule(types.KindAuthConnector, RW()),
types.NewRule(types.KindSession, RO()),
types.NewRule(types.KindTrustedCluster, RW()),
types.NewRule(types.KindEvent, RO()),
types.NewRule(types.KindClusterAuthPreference, RW()),
types.NewRule(types.KindClusterNetworkingConfig, RW()),
types.NewRule(types.KindSessionRecordingConfig, RW()),
types.NewRule(types.KindUIConfig, RW()),
types.NewRule(types.KindApp, RW()),
types.NewRule(types.KindDatabase, RW()),
types.NewRule(types.KindLock, RW()),
types.NewRule(types.KindToken, RW()),
types.NewRule(types.KindConnectionDiagnostic, RW()),
types.NewRule(types.KindKubernetesCluster, RW()),
types.NewRule(types.KindSessionTracker, RO()),
types.NewRule(types.KindUserGroup, RW()),
},
JoinSessions: []*types.SessionJoinPolicy{
{
Name: "foo",
Roles: []string{"*"},
Kinds: []string{string(types.SSHSessionKind)},
Modes: []string{string(types.SessionPeerMode)},
},
},
},
})
return role
}
// RoleForCertAuthority creates role using types.CertAuthority.
func RoleForCertAuthority(ca types.CertAuthority) types.Role {
role, _ := types.NewRole(RoleNameForCertAuthority(ca.GetClusterName()), types.RoleSpecV6{
Options: types.RoleOptions{
MaxSessionTTL: types.NewDuration(defaults.MaxCertDuration),
},
Allow: types.RoleConditions{
Namespaces: []string{defaults.Namespace},
NodeLabels: types.Labels{types.Wildcard: []string{types.Wildcard}},
AppLabels: types.Labels{types.Wildcard: []string{types.Wildcard}},
KubernetesLabels: types.Labels{types.Wildcard: []string{types.Wildcard}},
DatabaseLabels: types.Labels{types.Wildcard: []string{types.Wildcard}},
Rules: types.CopyRulesSlice(DefaultCertAuthorityRules),
},
})
return role
}
// ValidateRoleName checks that the role name is allowed to be created.
func ValidateRoleName(role types.Role) error {
// System role names are not allowed.
systemRoles := types.SystemRoles([]types.SystemRole{
types.SystemRole(role.GetMetadata().Name),
})
if err := systemRoles.Check(); err == nil {
return trace.BadParameter("reserved role: %s", role.GetMetadata().Name)
}
return nil
}
type validateRoleOptions struct {
warningReporter func(error)
}
func defaultValidateRoleOptions() validateRoleOptions {
return validateRoleOptions{
warningReporter: func(error) {},
}
}
type validateRoleOption func(*validateRoleOptions)
// withWarningReporter is meant for tests to assert the presence of expected
// warnings.
func withWarningReporter(f func(error)) validateRoleOption {
return func(opts *validateRoleOptions) {
opts.warningReporter = f
}
}
// ValidateRole parses validates the role, and sets default values.
func ValidateRole(r types.Role, opts ...validateRoleOption) error {
options := defaultValidateRoleOptions()
for _, opt := range opts {
opt(&options)
}
if err := r.CheckAndSetDefaults(); err != nil {
return err
}
// Expression parsers in new versions sometimes get smarter/more strict and
// catch more syntax or type errors that previously would only be caught
// when they were evaluated. To avoid any possibility of bricking a cluster
// by making all roles invalid due to a buggy expression that may not even
// be used, only log expression parse errors as a warning.
if err := validateRoleExpressions(r); err != nil {
options.warningReporter(err)
log.Warnf("Detected invalid role %q: %v", r.GetName(), err)
}
return nil
}
func validateRoleExpressions(r types.Role) error {
var errs []error
for _, condition := range []struct {
name string
condition types.RoleConditionType
}{
{"allow", types.Allow},
{"deny", types.Deny},
} {
for _, rule := range r.GetRules(condition.condition) {
if err := validateRule(rule); err != nil {
err = trace.BadParameter("parsing %s rule: %v", condition.name, err)
errs = append(errs, err)
}
}
for _, values := range []struct {
name string
values []string
}{
{"logins", r.GetLogins(condition.condition)},
{"windows_desktop_logins", r.GetWindowsLogins(condition.condition)},
{"aws_role_arns", r.GetAWSRoleARNs(condition.condition)},
{"azure_identities", r.GetAzureIdentities(condition.condition)},
{"gcp_service_accounts", r.GetGCPServiceAccounts(condition.condition)},
{"kubernetes_groups", r.GetKubeGroups(condition.condition)},
{"kubernetes_users", r.GetKubeUsers(condition.condition)},
{"db_names", r.GetDatabaseNames(condition.condition)},
{"db_users", r.GetDatabaseUsers(condition.condition)},
{"host_groups", r.GetHostGroups(condition.condition)},
{"host_sudeoers", r.GetHostSudoers(condition.condition)},
{"desktop_groups", r.GetDesktopGroups(condition.condition)},
{"impersonate.users", r.GetImpersonateConditions(condition.condition).Users},
{"impersonate.roles", r.GetImpersonateConditions(condition.condition).Roles},
} {
for _, value := range values.values {
_, err := parse.NewTraitsTemplateExpression(value)
if err != nil {
err = trace.BadParameter("parsing %s.%s expression: %v", condition.name, values.name, err)
errs = append(errs, err)
}
}
}
for _, labels := range []struct {
name string
kind string
}{
{"cluster_labels", types.KindRemoteCluster},
{"node_labels", types.KindNode},
{"kubernetes_labels", types.KindKubernetesCluster},
{"app_labels", types.KindApp},
{"db_labels", types.KindDatabase},
{"db_service_labels", types.KindDatabaseService},
{"windows_desktop_labels", types.KindWindowsDesktop},
{"group_labels", types.KindUserGroup},
} {
labelMatchers, err := r.GetLabelMatchers(condition.condition, labels.kind)
if err != nil {
return trace.Wrap(err)
}
for _, labelValues := range labelMatchers.Labels {
for _, label := range labelValues {
_, err := parse.NewTraitsTemplateExpression(label)
if err != nil {
err = trace.BadParameter("parsing %s.%s template expression: %v", condition.name, labels.name, err)
errs = append(errs, err)
}
}
}
if len(labelMatchers.Expression) > 0 {
if _, err := parseLabelExpression(labelMatchers.Expression); err != nil {
err = trace.BadParameter("parsing %s.%s_expression: %v", condition.name, labels.name, err)
errs = append(errs, err)
}
}
}
}
return trace.NewAggregate(errs...)
}
// validateRule parses the where and action fields to validate the rule.
func validateRule(r types.Rule) error {
if len(r.Where) != 0 {
parser, err := NewWhereParser(&Context{})
if err != nil {
return trace.Wrap(err)
}
_, err = parser.Parse(r.Where)
if err != nil {
return trace.BadParameter("could not parse 'where' rule: %q, error: %v", r.Where, err)
}
}
if len(r.Actions) != 0 {
parser, err := NewActionsParser(&Context{})
if err != nil {
return trace.Wrap(err)
}
for i, action := range r.Actions {
_, err = parser.Parse(action)
if err != nil {
return trace.BadParameter("could not parse action %v %q, error: %v", i, action, err)
}
}
}
return nil
}
func filterInvalidUnixLogins(candidates []string) []string {
var output []string
for _, candidate := range candidates {
if cstrings.IsValidUnixUser(candidate) {
// A valid variable was found in the traits, append it to the list of logins.
output = append(output, candidate)
continue
}
// Log any invalid logins which were added by a user but ignore any
// Teleport internal logins which are known to be invalid.
if candidate != teleport.SSHSessionJoinPrincipal && !strings.HasPrefix(candidate, "no-login-") {
log.Debugf("Skipping login %v, not a valid Unix login.", candidate)
}
}
return output
}
func filterInvalidWindowsLogins(candidates []string) []string {
var output []string
// https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-2000-server/bb726984(v=technet.10)
const invalidChars = `"/\[]:;|=,+*?<>`
for _, candidate := range candidates {
if strings.ContainsAny(candidate, invalidChars) {
log.Debugf("Skipping Windows login %v, not a valid Windows login.", candidate)
continue
}
output = append(output, candidate)
}
return output
}
func warnInvalidAzureIdentities(candidates []string) {
for _, candidate := range candidates {
if !MatchValidAzureIdentity(candidate) {
log.Warningf("Invalid format of Azure identity %q", candidate)
}
}
}
// ParseResourceID from Azure SDK is too lenient; we use a strict regexp instead.
var azureIdentityPattern = regexp.MustCompile(`(?i)^/subscriptions/([a-fA-F0-9-]+)/resourceGroups/([0-9a-zA-Z-_]+)/providers/Microsoft\.ManagedIdentity/userAssignedIdentities/([0-9a-zA-Z-_]+)$`)
func MatchValidAzureIdentity(identity string) bool {
if identity == types.Wildcard {
return true
}
return azureIdentityPattern.MatchString(identity)
}
// ApplyTraits applies the passed in traits to any variables within the role
// and returns itself.
func ApplyTraits(r types.Role, traits map[string][]string) (types.Role, error) {
for _, condition := range []types.RoleConditionType{types.Allow, types.Deny} {
inLogins := r.GetLogins(condition)
outLogins := applyValueTraitsSlice(inLogins, traits, "login")
outLogins = filterInvalidUnixLogins(outLogins)
r.SetLogins(condition, apiutils.Deduplicate(outLogins))
inWindowsLogins := r.GetWindowsLogins(condition)
outWindowsLogins := applyValueTraitsSlice(inWindowsLogins, traits, "windows_login")
outWindowsLogins = filterInvalidWindowsLogins(outWindowsLogins)
r.SetWindowsLogins(condition, apiutils.Deduplicate(outWindowsLogins))
inRoleARNs := r.GetAWSRoleARNs(condition)
outRoleARNs := applyValueTraitsSlice(inRoleARNs, traits, "AWS role ARN")
r.SetAWSRoleARNs(condition, apiutils.Deduplicate(outRoleARNs))
inAzureIdentities := r.GetAzureIdentities(condition)
outAzureIdentities := applyValueTraitsSlice(inAzureIdentities, traits, "Azure identity")
warnInvalidAzureIdentities(outAzureIdentities)
r.SetAzureIdentities(condition, apiutils.Deduplicate(outAzureIdentities))
inGCPAccounts := r.GetGCPServiceAccounts(condition)
outGCPAccounts := applyValueTraitsSlice(inGCPAccounts, traits, "GCP service account")
r.SetGCPServiceAccounts(condition, apiutils.Deduplicate(outGCPAccounts))
// apply templates to kubernetes groups
inKubeGroups := r.GetKubeGroups(condition)
outKubeGroups := applyValueTraitsSlice(inKubeGroups, traits, "kube group")
r.SetKubeGroups(condition, apiutils.Deduplicate(outKubeGroups))
// apply templates to kubernetes users
inKubeUsers := r.GetKubeUsers(condition)
outKubeUsers := applyValueTraitsSlice(inKubeUsers, traits, "kube user")
r.SetKubeUsers(condition, apiutils.Deduplicate(outKubeUsers))
// apply templates to database names
inDbNames := r.GetDatabaseNames(condition)
outDbNames := applyValueTraitsSlice(inDbNames, traits, "database name")
r.SetDatabaseNames(condition, apiutils.Deduplicate(outDbNames))
// apply templates to database users
inDbUsers := r.GetDatabaseUsers(condition)
outDbUsers := applyValueTraitsSlice(inDbUsers, traits, "database user")
r.SetDatabaseUsers(condition, apiutils.Deduplicate(outDbUsers))
// apply templates to database roles
inDbRoles := r.GetDatabaseRoles(condition)
outDbRoles := applyValueTraitsSlice(inDbRoles, traits, "database role")
r.SetDatabaseRoles(condition, apiutils.Deduplicate(outDbRoles))
for _, kind := range []string{
types.KindRemoteCluster,
types.KindNode,
types.KindKubernetesCluster,
types.KindApp,
types.KindDatabase,
types.KindDatabaseService,
types.KindWindowsDesktop,
types.KindUserGroup,
} {
labelMatchers, err := r.GetLabelMatchers(condition, kind)
if err != nil {
return nil, trace.Wrap(err)
}
// Only labelMatchers.Labels is templated, if empty we can skip
// these label matchers. labelMatchers.Expression can reference user
// traits later during the access check through the expression
// environment, they are not templated in here.
if len(labelMatchers.Labels) == 0 {
continue
}
labelMatchers.Labels = applyLabelsTraits(labelMatchers.Labels, traits)
if err := r.SetLabelMatchers(condition, kind, labelMatchers); err != nil {
return nil, trace.Wrap(err)
}
}
r.SetHostGroups(condition,
applyValueTraitsSlice(r.GetHostGroups(condition), traits, "host_groups"))
r.SetHostSudoers(condition,
applyValueTraitsSlice(r.GetHostSudoers(condition), traits, "host_sudoers"))
r.SetDesktopGroups(condition,
applyValueTraitsSlice(r.GetDesktopGroups(condition), traits, "desktop_groups"))
options := r.GetOptions()
for i, ext := range options.CertExtensions {
vals, err := ApplyValueTraits(ext.Value, traits)
if err != nil && !trace.IsNotFound(err) {
log.Warnf("Did not apply trait to cert_extensions.value: %v", err)
continue
}
if len(vals) != 0 {
options.CertExtensions[i].Value = vals[0]
}
}
// apply templates to impersonation conditions
inCond := r.GetImpersonateConditions(condition)
var outCond types.ImpersonateConditions
outCond.Users = applyValueTraitsSlice(inCond.Users, traits, "impersonate user")
outCond.Roles = applyValueTraitsSlice(inCond.Roles, traits, "impersonate role")
outCond.Users = apiutils.Deduplicate(outCond.Users)
outCond.Roles = apiutils.Deduplicate(outCond.Roles)
outCond.Where = inCond.Where
r.SetImpersonateConditions(condition, outCond)
}
return r, nil
}
// applyValueTraitsSlice iterates over a slice of input strings, calling
// ApplyValueTraits on each.
func applyValueTraitsSlice(inputs []string, traits map[string][]string, fieldName string) []string {
var output []string
for _, value := range inputs {
outputs, err := ApplyValueTraits(value, traits)
if err != nil {
if !trace.IsNotFound(err) {
log.WithError(err).Debugf("Skipping %s %q.", fieldName, value)
}
continue
}
output = append(output, outputs...)
}
return output
}
// applyLabelsTraits interpolates variables based on the templates
// and traits from identity provider. For example:
//
// cluster_labels:
//
// env: ['{{external.groups}}']
//
// and groups: ['admins', 'devs']
//
// will be interpolated to:
//
// cluster_labels:
//
// env: ['admins', 'devs']
func applyLabelsTraits(inLabels types.Labels, traits map[string][]string) types.Labels {
outLabels := make(types.Labels, len(inLabels))
// every key will be mapped to the first value
for key, vals := range inLabels {
keyVars, err := ApplyValueTraits(key, traits)
if err != nil {
// empty key will not match anything
log.Debugf("Setting empty node label pair %q -> %q: %v", key, vals, err)
keyVars = []string{""}
}
var values []string
for _, val := range vals {
valVars, err := ApplyValueTraits(val, traits)
if err != nil {
log.Debugf("Setting empty node label value %q -> %q: %v", key, val, err)
// empty value will not match anything
valVars = []string{""}
}
values = append(values, valVars...)
}
outLabels[keyVars[0]] = apiutils.Deduplicate(values)
}
return outLabels
}
// ApplyValueTraits applies the passed in traits to the variable,
// returns BadParameter in case if referenced variable is unsupported,
// returns NotFound in case if referenced trait is missing,
// mapped list of values otherwise, the function guarantees to return
// at least one value in case if return value is nil
func ApplyValueTraits(val string, traits map[string][]string) ([]string, error) {
// Extract the variable from the role variable.
expr, err := parse.NewTraitsTemplateExpression(val)
if err != nil {
return nil, trace.Wrap(err)
}
varValidation := func(namespace string, name string) error {
// verify that internal traits match the supported variables
if namespace == teleport.TraitInternalPrefix {
switch name {
case constants.TraitLogins, constants.TraitWindowsLogins,
constants.TraitKubeGroups, constants.TraitKubeUsers,
constants.TraitDBNames, constants.TraitDBUsers, constants.TraitDBRoles,
constants.TraitAWSRoleARNs, constants.TraitAzureIdentities,
constants.TraitGCPServiceAccounts, teleport.TraitJWT:
default:
return trace.BadParameter("unsupported variable %q", name)
}
}
// TODO: return a not found error if the variable namespace is not
// the namespace of `traits`.
// If e.g. the `traits` belong to the "internal" namespace (as the
// validation above suggests), and "foo" is a key in `traits`, then
// "external.foo" will return the value of "internal.foo". This is
// incorrect, and a not found error should be returned instead.
// This would be similar to the var validation done in getPAMConfig
// (lib/srv/ctx.go).
return nil
}
interpolated, err := expr.Interpolate(varValidation, traits)
if err != nil {
return nil, trace.Wrap(err)
}
if len(interpolated) == 0 {
return nil, trace.NotFound("variable interpolation result is empty")
}
return interpolated, nil
}
// ruleScore is a sorting score of the rule, the larger the score, the more
// specific the rule is
func ruleScore(r *types.Rule) int {
score := 0
// wildcard rules are less specific
if slices.Contains(r.Resources, types.Wildcard) {
score -= 4
} else if len(r.Resources) == 1 {
// rules that match specific resource are more specific than
// fields that match several resources
score += 2
}
// rules that have wildcard verbs are less specific
if slices.Contains(r.Verbs, types.Wildcard) {
score -= 2
}
// rules that supply 'where' or 'actions' are more specific
// having 'where' or 'actions' is more important than
// whether the rules are wildcard or not, so here we have +8 vs
// -4 and -2 score penalty for wildcards in resources and verbs
if len(r.Where) > 0 {
score += 8
}
// rules featuring actions are more specific
if len(r.Actions) > 0 {
score += 8
}
return score
}
// CompareRuleScore returns true if the first rule is more specific than the other.
//
// * nRule matching wildcard resource is less specific
// than same rule matching specific resource.
// * Rule that has wildcard verbs is less specific
// than the same rules matching specific verb.
// * Rule that has where section is more specific
// than the same rule without where section.
// * Rule that has actions list is more specific than
// rule without actions list.
func CompareRuleScore(r *types.Rule, o *types.Rule) bool {
return ruleScore(r) > ruleScore(o)
}
// RuleSet maps resource to a set of rules defined for it
type RuleSet map[string][]types.Rule
// MakeRuleSet creates a new rule set from a list
func MakeRuleSet(rules []types.Rule) RuleSet {
set := make(RuleSet)
for _, rule := range rules {
for _, resource := range rule.Resources {
set[resource] = append(set[resource], rule)
}
}
for resource := range set {
rules := set[resource]
// sort rules by most specific rule, the rule that has actions
// is more specific than the one that has no actions
sort.Slice(rules, func(i, j int) bool {
return CompareRuleScore(&rules[i], &rules[j])
})
set[resource] = rules
}
return set
}
// Match tests if the resource name and verb are in a given list of rules.
// More specific rules will be matched first. See Rule.IsMoreSpecificThan
// for exact specs on whether the rule is more or less specific.
//
// Specifying order solves the problem on having multiple rules, e.g. one wildcard
// rule can override more specific rules with 'where' sections that can have
// 'actions' lists with side effects that will not be triggered otherwise.
func (set RuleSet) Match(whereParser predicate.Parser, actionsParser predicate.Parser, resource string, verb string) (bool, error) {
// empty set matches nothing
if len(set) == 0 {
return false, nil
}
// check for matching resource by name
// the most specific rule should win
rules := set[resource]
for _, rule := range rules {
match, err := matchesWhere(&rule, whereParser)
if err != nil {
return false, trace.Wrap(err)
}
if match && (rule.HasVerb(types.Wildcard) || rule.HasVerb(verb)) {
if err := processActions(&rule, actionsParser); err != nil {
return true, trace.Wrap(err)
}
return true, nil
}
}
// check for wildcard resource matcher
for _, rule := range set[types.Wildcard] {
match, err := matchesWhere(&rule, whereParser)
if err != nil {
return false, trace.Wrap(err)
}
if match && (rule.HasVerb(types.Wildcard) || rule.HasVerb(verb)) {
if err := processActions(&rule, actionsParser); err != nil {
return true, trace.Wrap(err)
}
return true, nil
}
}
return false, nil
}
// matchesWhere returns true if Where rule matches.
// Empty Where block always matches.
func matchesWhere(r *types.Rule, parser predicate.Parser) (bool, error) {
if r.Where == "" {
return true, nil
}
ifn, err := parser.Parse(r.Where)
if err != nil {
return false, trace.Wrap(err)
}
fn, ok := ifn.(predicate.BoolPredicate)
if !ok {
return false, trace.BadParameter("invalid predicate type for where expression: %v", r.Where)
}
return fn(), nil
}
// processActions processes actions specified for this rule
func processActions(r *types.Rule, parser predicate.Parser) error {
for _, action := range r.Actions {
ifn, err := parser.Parse(action)
if err != nil {
return trace.Wrap(err)
}
fn, ok := ifn.(predicate.BoolPredicate)
if !ok {
return trace.BadParameter("invalid predicate type for action expression: %v", action)
}
fn()
}
return nil
}
// Slice returns slice from a set
func (set RuleSet) Slice() []types.Rule {
var out []types.Rule
for _, rules := range set {
out = append(out, rules...)
}
return out
}
// HostUsersInfo keeps information about groups and sudoers entries
// for a particular host user
type HostUsersInfo struct {
// Groups is the list of groups to include host users in
Groups []string
// Sudoers is a list of entries for a users sudoers file
Sudoers []string
}
// RoleFromSpec returns new Role created from spec
func RoleFromSpec(name string, spec types.RoleSpecV6) (types.Role, error) {
role, err := types.NewRole(name, spec)
return role, trace.Wrap(err)
}
// RoleSetFromSpec returns a new RoleSet from spec
func RoleSetFromSpec(name string, spec types.RoleSpecV6) (RoleSet, error) {
role, err := RoleFromSpec(name, spec)
if err != nil {
return nil, trace.Wrap(err)
}
return NewRoleSet(role), nil
}
// RW is a shortcut that returns all CRUD verbs.
func RW() []string {
return []string{types.VerbList, types.VerbCreate, types.VerbRead, types.VerbUpdate, types.VerbDelete}
}
// RO is a shortcut that returns read only verbs that provide access to secrets.
func RO() []string {
return []string{types.VerbList, types.VerbRead}
}
// ReadNoSecrets is a shortcut that returns read only verbs that do not
// provide access to secrets.
func ReadNoSecrets() []string {
return []string{types.VerbList, types.VerbReadNoSecrets}
}
// RoleGetter is an interface that defines GetRole method
type RoleGetter interface {
// GetRole returns role by name
GetRole(ctx context.Context, name string) (types.Role, error)
}
// ExtractFromCertificate will extract roles and traits from a *ssh.Certificate.
func ExtractFromCertificate(cert *ssh.Certificate) ([]string, wrappers.Traits, error) {
roles, err := ExtractRolesFromCert(cert)
if err != nil {
return nil, nil, trace.Wrap(err)
}
traits, err := ExtractTraitsFromCert(cert)
if err != nil {
return nil, nil, trace.Wrap(err)
}
return roles, traits, nil
}
// ExtractFromIdentity will extract roles and traits from the *x509.Certificate
// which Teleport passes along as a *tlsca.Identity. If roles and traits do not
// exist in the certificates, they are extracted from the backend.
func ExtractFromIdentity(access UserGetter, identity tlsca.Identity) ([]string, wrappers.Traits, error) {
// Legacy certs are not encoded with roles or traits,
// so we fallback to the traits and roles in the backend.
// empty traits are a valid use case in standard certs,
// so we only check for whether roles are empty.
if len(identity.Groups) == 0 {
u, err := access.GetUser(identity.Username, false)
if err != nil {
return nil, nil, trace.Wrap(err)
}
log.Warnf("Failed to find roles in x509 identity for %v. Fetching "+
"from backend. If the identity provider allows username changes, this can "+
"potentially allow an attacker to change the role of the existing user.",
identity.Username)
return u.GetRoles(), u.GetTraits(), nil
}
return identity.Groups, identity.Traits, nil
}
// FetchRoleList fetches roles by their names, applies the traits to role
// variables, and returns the list
func FetchRoleList(roleNames []string, access RoleGetter, traits map[string][]string) (RoleSet, error) {
var roles []types.Role
for _, roleName := range roleNames {
role, err := access.GetRole(context.TODO(), roleName)
if err != nil {
return nil, trace.Wrap(err)
}
role, err = ApplyTraits(role, traits)
if err != nil {
return nil, trace.Wrap(err)
}
roles = append(roles, role)
}
return roles, nil
}
// FetchRoles fetches roles by their names, applies the traits to role
// variables, and returns the RoleSet. Adds runtime roles like the default
// implicit role to RoleSet.
func FetchRoles(roleNames []string, access RoleGetter, traits map[string][]string) (RoleSet, error) {
roles, err := FetchRoleList(roleNames, access, traits)
if err != nil {
return nil, trace.Wrap(err)
}
return NewRoleSet(roles...), nil
}
// ExtractRolesFromCert extracts roles from certificate metadata extensions.
func ExtractRolesFromCert(cert *ssh.Certificate) ([]string, error) {
data, ok := cert.Extensions[teleport.CertExtensionTeleportRoles]
if !ok {
return nil, trace.NotFound("no roles found")
}
return UnmarshalCertRoles(data)
}
// ExtractTraitsFromCert extracts traits from the certificate extensions.
func ExtractTraitsFromCert(cert *ssh.Certificate) (wrappers.Traits, error) {
rawTraits, ok := cert.Extensions[teleport.CertExtensionTeleportTraits]
if !ok {
return nil, trace.NotFound("no traits found")
}
var traits wrappers.Traits
err := wrappers.UnmarshalTraits([]byte(rawTraits), &traits)
if err != nil {
return nil, trace.Wrap(err)
}
return traits, nil
}
func ExtractAllowedResourcesFromCert(cert *ssh.Certificate) ([]types.ResourceID, error) {
allowedResourcesStr, ok := cert.Extensions[teleport.CertExtensionAllowedResources]
if !ok {
// if not present in the cert, there are no resource-based restrictions
return nil, nil
}
allowedResources, err := types.ResourceIDsFromString(allowedResourcesStr)
return allowedResources, trace.Wrap(err)
}
// NewRoleSet returns new RoleSet based on the roles
func NewRoleSet(roles ...types.Role) RoleSet {
// unauthenticated Nop role should not have any privileges
// by default, otherwise it is too permissive
if len(roles) == 1 && roles[0].GetName() == string(types.RoleNop) {
return roles
}
return append(roles, NewImplicitRole())
}
// 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
}