聊聊spring security的role hierarchy

序

本文就来研究一下spring security的role hierarchy

背景

默认情况下，userDetailsService建立的用户，他们的权限是没有继承关系的

    @Bean
    @Override
    protected UserDetailsService userDetailsService(){
        InMemoryUserDetailsManager manager = new InMemoryUserDetailsManager();
        manager.createUser(User.withUsername("demoUser1").password("123456")
                .authorities("ROLE_USER","read_x").build());
        manager.createUser(User.withUsername("admin").password("123456")
                .authorities("ROLE_ADMIN").build());
        return manager;
    }

比如这两个

    @GetMapping("/admin")
    @Secured("ROLE_ADMIN")
    public String admin(){
        return "admin";
    }

    @GetMapping("/user")
    @Secured("ROLE_USER")
    public String user(){
        return "user";
    }

admin登录只能访问/admin，访问不了/user；而user登录只能访问/user

这通常不大符合我们的业务需求，一般admin拥有所有权限的，也就是它应该能访问/user。这个问题扩展开来就是角色权限的继承问题，role hierarchy

RoleHierarchy

spring-security-core-4.2.3.RELEASE-sources.jar!/org/springframework/security/access/hierarchicalroles/RoleHierarchy.java

            ROLE_ADMIN > ROLE_STAFF
            ROLE_STAFF > ROLE_USER
            ROLE_USER > ROLE_GUEST

spring security提供了RoleHierarchy，可以让你去定义各类角色的层级关系

config

@EnableGlobalMethodSecurity(
        securedEnabled = true,
        jsr250Enabled = true,
        prePostEnabled = true
)
@Configuration
public class RoleConfig extends GlobalMethodSecurityConfiguration{

    @Override
    protected AccessDecisionManager accessDecisionManager() {
        List<AccessDecisionVoter<? extends Object>> decisionVoters = new ArrayList<AccessDecisionVoter<? extends Object>>();
        ExpressionBasedPreInvocationAdvice expressionAdvice = new ExpressionBasedPreInvocationAdvice();
        expressionAdvice.setExpressionHandler(getExpressionHandler());
//        if (prePostEnabled()) {
            decisionVoters
                    .add(new PreInvocationAuthorizationAdviceVoter(expressionAdvice));
//        }
//        if (jsr250Enabled()) {
            decisionVoters.add(new Jsr250Voter());
//        }
//        decisionVoters.add(new RoleVoter());
        decisionVoters.add(roleHierarchyVoter());
        decisionVoters.add(new AuthenticatedVoter());

        return new AffirmativeBased(decisionVoters);
    }


    @Bean
    public RoleHierarchyVoter roleHierarchyVoter() {
        return new RoleHierarchyVoter(roleHierarchy());
    }

    @Bean
    public RoleHierarchy roleHierarchy(){
        RoleHierarchyImpl roleHierarchy = new RoleHierarchyImpl();
        roleHierarchy.setHierarchy(
                "ROLE_ADMIN > ROLE_USER\n"+
                        " ROLE_USER > ROLE_ANONYMOUS\n"
        );
        return roleHierarchy;
    }
}

这里通过重写GlobalMethodSecurityConfiguration的accessDecisionManager方法，给decisionVoters添加roleHierarchyVoter
默认是使用RoleVoter，它不支持继承关系，这里替换为roleHierarchyVoter
这样就大功告成了，admin也可以访问user权限的页面/接口

RoleHierarchyVoter

spring-security-core-4.2.3.RELEASE-sources.jar!/org/springframework/security/access/vote/RoleHierarchyVoter.java

/**
 * Extended RoleVoter which uses a {@link RoleHierarchy} definition to determine the roles
 * allocated to the current user before voting.
 *
 * @author Luke Taylor
 * @since 2.0.4
 */
public class RoleHierarchyVoter extends RoleVoter {
    private RoleHierarchy roleHierarchy = null;

    public RoleHierarchyVoter(RoleHierarchy roleHierarchy) {
        Assert.notNull(roleHierarchy, "RoleHierarchy must not be null");
        this.roleHierarchy = roleHierarchy;
    }

    /**
     * Calls the <tt>RoleHierarchy</tt> to obtain the complete set of user authorities.
     */
    @Override
    Collection<? extends GrantedAuthority> extractAuthorities(
            Authentication authentication) {
        return roleHierarchy.getReachableGrantedAuthorities(authentication
                .getAuthorities());
    }
}

这类继承了RoleVoter，重写了extractAuthorities，使用roleHierarchy去获取grantedAuthorities

继承关系的构建

spring-security-core-4.2.3.RELEASE-sources.jar!/org/springframework/security/access/hierarchicalroles/RoleHierarchyImpl.java

    /**
     * Set the role hierarchy and pre-calculate for every role the set of all reachable
     * roles, i.e. all roles lower in the hierarchy of every given role. Pre-calculation
     * is done for performance reasons (reachable roles can then be calculated in O(1)
     * time). During pre-calculation, cycles in role hierarchy are detected and will cause
     * a <tt>CycleInRoleHierarchyException</tt> to be thrown.
     *
     * @param roleHierarchyStringRepresentation - String definition of the role hierarchy.
     */
    public void setHierarchy(String roleHierarchyStringRepresentation) {
        this.roleHierarchyStringRepresentation = roleHierarchyStringRepresentation;

        logger.debug("setHierarchy() - The following role hierarchy was set: "
                + roleHierarchyStringRepresentation);

        buildRolesReachableInOneStepMap();
        buildRolesReachableInOneOrMoreStepsMap();
    }

设置层级关系之后，通过buildRolesReachableInOneStepMap以及buildRolesReachableInOneOrMoreStepsMap这两个方法去构建映射

buildRolesReachableInOneStepMap

    /**
     * rolesReachableInOneStepMap is a Map that under the key of a specific role name
     * contains a set of all roles reachable from this role in 1 step
     */
    private Map<GrantedAuthority, Set<GrantedAuthority>> rolesReachableInOneStepMap = null;

    /**
     * Parse input and build the map for the roles reachable in one step: the higher role
     * will become a key that references a set of the reachable lower roles.
     */
    private void buildRolesReachableInOneStepMap() {
        Pattern pattern = Pattern.compile("(\\s*([^\\s>]+)\\s*>\\s*([^\\s>]+))");

        Matcher roleHierarchyMatcher = pattern
                .matcher(this.roleHierarchyStringRepresentation);
        this.rolesReachableInOneStepMap = new HashMap<GrantedAuthority, Set<GrantedAuthority>>();

        while (roleHierarchyMatcher.find()) {
            GrantedAuthority higherRole = new SimpleGrantedAuthority(
                    roleHierarchyMatcher.group(2));
            GrantedAuthority lowerRole = new SimpleGrantedAuthority(
                    roleHierarchyMatcher.group(3));
            Set<GrantedAuthority> rolesReachableInOneStepSet;

            if (!this.rolesReachableInOneStepMap.containsKey(higherRole)) {
                rolesReachableInOneStepSet = new HashSet<GrantedAuthority>();
                this.rolesReachableInOneStepMap.put(higherRole,
                        rolesReachableInOneStepSet);
            }
            else {
                rolesReachableInOneStepSet = this.rolesReachableInOneStepMap
                        .get(higherRole);
            }
            addReachableRoles(rolesReachableInOneStepSet, lowerRole);

            logger.debug("buildRolesReachableInOneStepMap() - From role " + higherRole
                    + " one can reach role " + lowerRole + " in one step.");
        }
    }

    private void addReachableRoles(Set<GrantedAuthority> reachableRoles,
            GrantedAuthority authority) {

        for (GrantedAuthority testAuthority : reachableRoles) {
            String testKey = testAuthority.getAuthority();
            if ((testKey != null) && (testKey.equals(authority.getAuthority()))) {
                return;
            }
        }
        reachableRoles.add(authority);
    }

Map<GrantedAuthority, Set<GrantedAuthority>> rolesReachableInOneStepMap ，这里将第一级的直连关系存到这个map当中

假设级联关系是

A > B
B > C
C > D
D > E
D > F

那么这个map就类似于

A --> [B]
B --> [C]
C --> [D]
D --> [E,F]

buildRolesReachableInOneOrMoreStepsMap

    /**
     * rolesReachableInOneOrMoreStepsMap is a Map that under the key of a specific role
     * name contains a set of all roles reachable from this role in 1 or more steps
     */
    private Map<GrantedAuthority, Set<GrantedAuthority>> rolesReachableInOneOrMoreStepsMap = null;

    /**
     * For every higher role from rolesReachableInOneStepMap store all roles that are
     * reachable from it in the map of roles reachable in one or more steps. (Or throw a
     * CycleInRoleHierarchyException if a cycle in the role hierarchy definition is
     * detected)
     */
    private void buildRolesReachableInOneOrMoreStepsMap() {
        this.rolesReachableInOneOrMoreStepsMap = new HashMap<GrantedAuthority, Set<GrantedAuthority>>();
        // iterate over all higher roles from rolesReachableInOneStepMap

        for (GrantedAuthority role : this.rolesReachableInOneStepMap.keySet()) {
            Set<GrantedAuthority> rolesToVisitSet = new HashSet<GrantedAuthority>();

            if (this.rolesReachableInOneStepMap.containsKey(role)) {
                rolesToVisitSet.addAll(this.rolesReachableInOneStepMap.get(role));
            }

            Set<GrantedAuthority> visitedRolesSet = new HashSet<GrantedAuthority>();

            while (!rolesToVisitSet.isEmpty()) {
                // take a role from the rolesToVisit set
                GrantedAuthority aRole = rolesToVisitSet.iterator().next();
                rolesToVisitSet.remove(aRole);
                addReachableRoles(visitedRolesSet, aRole);
                if (this.rolesReachableInOneStepMap.containsKey(aRole)) {
                    Set<GrantedAuthority> newReachableRoles = this.rolesReachableInOneStepMap
                            .get(aRole);

                    // definition of a cycle: you can reach the role you are starting from
                    if (rolesToVisitSet.contains(role)
                            || visitedRolesSet.contains(role)) {
                        throw new CycleInRoleHierarchyException();
                    }
                    else {
                        // no cycle
                        rolesToVisitSet.addAll(newReachableRoles);
                    }
                }
            }
            this.rolesReachableInOneOrMoreStepsMap.put(role, visitedRolesSet);

            logger.debug("buildRolesReachableInOneOrMoreStepsMap() - From role " + role
                    + " one can reach " + visitedRolesSet + " in one or more steps.");
        }

    }

Map<GrantedAuthority, Set<GrantedAuthority>> rolesReachableInOneOrMoreStepsMap这个将间接的层级关系拉平
这里实际用了递归来完成层级的所有级联关系映射，rolesToVisitSet不断remove和有条件地add，递归终止条件是rolesToVisitSet为empty

一级的map如下

A --> [B]
B --> [C]
C --> [D]
D --> [E,F]

构造完之后如下

A --> [B,C,D,E,F]
B --> [C,D,E,F]
C --> [D,E,F]
D --> [E,F]

RoleHierarchyImpl