[FEATURE] Support for subject combinations in ACLs (#1142)

docs/configuration/access-control.md

@@ -70,6 +70,11 @@ For a user with unique identifier `john`, the subject should be `user:john` and
 uniquely identified by `developers`, the subject should be `group:developers`. Similar to resources
 and domains you can define multiple subjects in a single rule.
 
+If you want a combination of subjects to be matched at once, you can specify a list of subjects like
+`- ["group:developers", "group:admins"]`. Make sure to preceed it by a list key `-`.
+In summary, the first level of subjects are evaluated using a logical `OR`, whereas the second level 
+by a logical `AND`.
+
 ## Networks
 
 A list of network ranges can be specified in a rule in order to apply different policies when
@@ -128,6 +133,7 @@ access_control:
     - domain: dev.example.com
       resources:
       - "^/users/john/.*$"
-      subject: "user:john"
+      subject: 
+      - ["group:dev", "user:john"]
       policy: two_factor
 ```

internal/authorization/authorizer.go

@@ -138,8 +138,10 @@ func (p *Authorizer) IsURLMatchingRuleWithGroupSubjects(requestURL url.URL) (has
 	for _, rule := range p.configuration.Rules {
 		if isDomainMatching(requestURL.Hostname(), rule.Domains) && isPathMatching(requestURL.Path, rule.Resources) {
 			for _, subjectRule := range rule.Subjects {
-				if strings.HasPrefix(subjectRule, groupPrefix) {
-					return true
+				for _, subject := range subjectRule {
+					if strings.HasPrefix(subject, groupPrefix) {
+						return true
+					}
 				}
 			}
 		}

internal/authorization/authorizer_test.go

@@ -166,7 +166,7 @@ func (s *AuthorizerSuite) TestShouldCheckRulePrecedence() {
 		WithRule(schema.ACLRule{
 			Domains:  []string{"protected.example.com"},
 			Policy:   "bypass",
-			Subjects: []string{"user:john"},
+			Subjects: [][]string{{"user:john"}},
 		}).
 		WithRule(schema.ACLRule{
 			Domains: []string{"protected.example.com"},
@@ -189,7 +189,7 @@ func (s *AuthorizerSuite) TestShouldCheckUserMatching() {
 		WithRule(schema.ACLRule{
 			Domains:  []string{"protected.example.com"},
 			Policy:   "bypass",
-			Subjects: []string{"user:john"},
+			Subjects: [][]string{{"user:john"}},
 		}).
 		Build()
 
@@ -203,7 +203,7 @@ func (s *AuthorizerSuite) TestShouldCheckGroupMatching() {
 		WithRule(schema.ACLRule{
 			Domains:  []string{"protected.example.com"},
 			Policy:   "bypass",
-			Subjects: []string{"group:admins"},
+			Subjects: [][]string{{"group:admins"}},
 		}).
 		Build()
 
@@ -217,7 +217,7 @@ func (s *AuthorizerSuite) TestShouldCheckSubjectsMatching() {
 		WithRule(schema.ACLRule{
 			Domains:  []string{"protected.example.com"},
 			Policy:   "bypass",
-			Subjects: []string{"group:admins", "user:bob"},
+			Subjects: [][]string{{"group:admins"}, {"user:bob"}},
 		}).
 		Build()
 
@@ -226,6 +226,21 @@ func (s *AuthorizerSuite) TestShouldCheckSubjectsMatching() {
 	tester.CheckAuthorizations(s.T(), AnonymousUser, "https://protected.example.com/", Denied)
 }
 
+func (s *AuthorizerSuite) TestShouldCheckMultipleSubjectsMatching() {
+	tester := NewAuthorizerBuilder().
+		WithDefaultPolicy("deny").
+		WithRule(schema.ACLRule{
+			Domains:  []string{"protected.example.com"},
+			Policy:   "bypass",
+			Subjects: [][]string{{"group:admins", "user:bob"}, {"group:admins", "group:dev"}},
+		}).
+		Build()
+
+	tester.CheckAuthorizations(s.T(), John, "https://protected.example.com/", Bypass)
+	tester.CheckAuthorizations(s.T(), Bob, "https://protected.example.com/", Denied)
+	tester.CheckAuthorizations(s.T(), AnonymousUser, "https://protected.example.com/", Denied)
+}
+
 func (s *AuthorizerSuite) TestShouldCheckIPMatching() {
 	tester := NewAuthorizerBuilder().
 		WithDefaultPolicy("deny").

internal/authorization/subject_matcher.go

@@ -6,25 +6,29 @@ import (
 	"github.com/authelia/authelia/internal/utils"
 )
 
-func isSubjectMatching(subject Subject, subjectRule string) bool {
-	// If no subject is provided in the rule, we match any user.
-	if subjectRule == "" {
-		return true
-	}
-
-	if strings.HasPrefix(subjectRule, userPrefix) {
-		user := strings.Trim(subjectRule[len(userPrefix):], " ")
-		if user == subject.Username {
-			return true
+func isSubjectMatching(subject Subject, subjectRule []string) bool {
+	for _, ruleSubject := range subjectRule {
+		// If no subject is provided in the rule, we match any user.
+		if ruleSubject == "" {
+			continue
 		}
-	}
 
-	if strings.HasPrefix(subjectRule, groupPrefix) {
-		group := strings.Trim(subjectRule[len(groupPrefix):], " ")
-		if utils.IsStringInSlice(group, subject.Groups) {
-			return true
+		if strings.HasPrefix(ruleSubject, userPrefix) {
+			user := strings.Trim(ruleSubject[len(userPrefix):], " ")
+			if user == subject.Username {
+				continue
+			}
 		}
+
+		if strings.HasPrefix(ruleSubject, groupPrefix) {
+			group := strings.Trim(ruleSubject[len(groupPrefix):], " ")
+			if utils.IsStringInSlice(group, subject.Groups) {
+				continue
+			}
+		}
+
+		return false
 	}
 
-	return false
+	return true
 }

internal/configuration/schema/access_control.go

@@ -6,13 +6,13 @@ import (
 	"strings"
 )
 
-// ACLRule represent one ACL rule "weak" coerces a single value into string slice.
+// ACLRule represents one ACL rule entry; "weak" coerces a single value into slice.
 type ACLRule struct {
-	Domains   []string `mapstructure:"domain,weak"`
-	Policy    string   `mapstructure:"policy"`
-	Subjects  []string `mapstructure:"subject,weak"`
-	Networks  []string `mapstructure:"networks"`
-	Resources []string `mapstructure:"resources"`
+	Domains   []string   `mapstructure:"domain,weak"`
+	Policy    string     `mapstructure:"policy"`
+	Subjects  [][]string `mapstructure:"subject,weak"`
+	Networks  []string   `mapstructure:"networks"`
+	Resources []string   `mapstructure:"resources"`
 }
 
 // IsPolicyValid check if policy is valid.
@@ -41,9 +41,11 @@ func (r *ACLRule) Validate(validator *StructValidator) {
 		validator.Push(fmt.Errorf("A policy must either be 'deny', 'two_factor', 'one_factor' or 'bypass'"))
 	}
 
-	for i, subject := range r.Subjects {
-		if !IsSubjectValid(subject) {
-			validator.Push(fmt.Errorf("Subject %d must start with 'user:' or 'group:'", i))
+	for i, subjectRule := range r.Subjects {
+		for j, subject := range subjectRule {
+			if !IsSubjectValid(subject) {
+				validator.Push(fmt.Errorf("Subject %d-%d must start with 'user:' or 'group:'", i, j))
+			}
 		}
 	}
 

internal/mocks/mock_authelia_ctx.go

@@ -85,11 +85,11 @@ func NewMockAutheliaCtx(t *testing.T) *MockAutheliaCtx {
 	}, {
 		Domains:  []string{"admin.example.com"},
 		Policy:   "two_factor",
-		Subjects: []string{"group:admin"},
+		Subjects: [][]string{{"group:admin"}},
 	}, {
 		Domains:  []string{"grafana.example.com"},
 		Policy:   "two_factor",
-		Subjects: []string{"group:grafana"},
+		Subjects: [][]string{{"group:grafana"}},
 	}}
 
 	providers := middlewares.Providers{}