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Add negative RBAC label matches #4253

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merged 4 commits into from
Sep 29, 2020
Merged

Add negative RBAC label matches #4253

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0c54ea8
utils/parse: rewrite tests in the new RFD style
Sep 17, 2020
5d54673
utils/parse: support string literal expressions
Sep 17, 2020
2a52efa
utils/parse: implement Matcher
Sep 17, 2020
45cf28b
Migrate services.MatchLabels to parse.Matcher
Sep 17, 2020
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27 changes: 16 additions & 11 deletions lib/services/role.go
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Original file line number Diff line number Diff line change
Expand Up @@ -385,12 +385,9 @@ func ApplyTraits(r Role, traits map[string][]string) Role {
// 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.
variable, err := parse.RoleVariable(val)
variable, err := parse.NewExpression(val)
if err != nil {
if !trace.IsNotFound(err) {
return nil, trace.Wrap(err)
}
return []string{val}, nil
return nil, trace.Wrap(err)
}

// For internal traits, only internal.logins, internal.kubernetes_users and
Expand Down Expand Up @@ -690,7 +687,7 @@ func (r *RoleV3) CheckAndSetDefaults() error {
for _, condition := range []RoleConditionType{Allow, Deny} {
for _, login := range r.GetLogins(condition) {
if strings.Contains(login, "{{") || strings.Contains(login, "}}") {
_, err := parse.RoleVariable(login)
_, err := parse.NewExpression(login)
if err != nil {
return trace.BadParameter("invalid login found: %v", login)
}
Expand Down Expand Up @@ -1588,11 +1585,19 @@ func MatchLabels(selector Labels, target map[string]string) (bool, string, error
}

if !utils.SliceContainsStr(selectorValues, Wildcard) {
result, err := utils.SliceMatchesRegex(targetVal, selectorValues)
if err != nil {
return false, "", trace.Wrap(err)
} else if !result {
return false, fmt.Sprintf("no value match: got '%v' want: '%v'", targetVal, selectorValues), nil
matched := false
for _, expr := range selectorValues {
m, err := parse.NewMatcher(expr)
if err != nil {
return false, "", trace.Wrap(err)
}
if m.Match(targetVal) {
matched = true
break
}
}
if !matched {
return false, fmt.Sprintf("no value match: got %q want: %q", targetVal, selectorValues), nil
}
}
}
Expand Down
58 changes: 58 additions & 0 deletions lib/services/role_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -749,6 +749,64 @@ func (s *RoleSuite) TestCheckAccess(c *C) {
{server: serverC2, login: "admin", hasAccess: true},
},
},
{
name: "role matches a regexp label",
roles: []RoleV3{
RoleV3{
Metadata: Metadata{
Name: "name1",
Namespace: defaults.Namespace,
},
Spec: RoleSpecV3{
Options: RoleOptions{
MaxSessionTTL: Duration(20 * time.Hour),
},
Allow: RoleConditions{
Logins: []string{"admin"},
NodeLabels: Labels{"role": []string{`{{regexp.match("worker.*")}}`}},
Namespaces: []string{defaults.Namespace, namespaceC},
},
},
},
},
checks: []check{
{server: serverA, login: "root", hasAccess: false},
{server: serverA, login: "admin", hasAccess: false},
{server: serverB, login: "root", hasAccess: false},
{server: serverB, login: "admin", hasAccess: true},
{server: serverC, login: "root", hasAccess: false},
{server: serverC, login: "admin", hasAccess: false},
},
},
{
name: "role matches a negative regexp label",
roles: []RoleV3{
RoleV3{
Metadata: Metadata{
Name: "name1",
Namespace: defaults.Namespace,
},
Spec: RoleSpecV3{
Options: RoleOptions{
MaxSessionTTL: Duration(20 * time.Hour),
},
Allow: RoleConditions{
Logins: []string{"admin"},
NodeLabels: Labels{"role": []string{`{{regexp.not_match("db.*")}}`}},
Namespaces: []string{defaults.Namespace, namespaceC},
},
},
},
},
checks: []check{
{server: serverA, login: "root", hasAccess: false},
{server: serverA, login: "admin", hasAccess: false},
{server: serverB, login: "root", hasAccess: false},
{server: serverB, login: "admin", hasAccess: true},
{server: serverC, login: "root", hasAccess: false},
{server: serverC, login: "admin", hasAccess: false},
},
},
}
for i, tc := range testCases {

Expand Down
4 changes: 2 additions & 2 deletions lib/services/user.go
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Original file line number Diff line number Diff line change
Expand Up @@ -491,8 +491,8 @@ func (u *UserV1) Check() error {
return trace.BadParameter("user name cannot be empty")
}
for _, login := range u.AllowedLogins {
_, err := parse.RoleVariable(login)
if err == nil {
e, err := parse.NewExpression(login)
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New logic only returns error in case of grammatic errors and accepts literal values. Doesn't it mean that now err should return error here if it's not nil? Otherwise the following will be accepted: {{regexp_not_match(...) which probably should not be ignored as it's a typo and we should let users know

if err == nil && e.Namespace() != parse.LiteralNamespace {
return trace.BadParameter("role variables not allowed in allowed logins")
}
}
Expand Down
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